Subtitle Downloader

extract video files into captioned video files with this skill. Works with MP4, MOV, AVI, WebM files up to 500MB. content creators use it for downloading sub...

Security Scan

The skill's requests and runtime instructions align with a remote subtitle-extraction service: it legitimately needs an API token and network access to upload/process videos; no unexpected credentials, installs, or privileged persistence are requested.

Purpose & Capability

The name/description (extract video subtitles, render 1080p MP4) matches the actions described in SKILL.md (create session, upload video, request render/export). Requesting a single service token (NEMO_TOKEN) is appropriate for this API-based workflow. One minor inconsistency: the SKILL.md frontmatter lists a config path (~/.config/nemovideo/) while the registry metadata said no required config paths.

Instruction Scope

Instructions are focused on establishing an API session, uploading video (multipart or URL), polling render status, and returning a download URL. They instruct reading the skill's own frontmatter and detecting an install path (~/.clawhub/, ~/.cursor/skills/) to set an attribution header — this requires checking standard user paths but does not instruct accessing unrelated files. The flow also includes obtaining an anonymous token if NEMO_TOKEN is absent (network POST).

Install Mechanism

Instruction-only skill with no install spec and no code files — lowest-risk install surface (nothing written to disk by an installer).

Credentials

Only NEMO_TOKEN is declared as required (primary credential), which is proportionate for a cloud API. The SKILL.md also references a config path in its metadata (possible local config read) and will use an anonymous-token fallback if no token is set. There are no unrelated credentials requested.

Persistence & Privilege

always:false and normal autonomous invocation are used. The skill does not request permanent presence, nor does it instruct modifying other skills or system-wide settings.

Assessment

This skill appears coherent for a cloud-based subtitle extraction service, but review these points before installing or using it: 1) It will send your video files (or file URLs) to https://mega-api-prod.nemovideo.ai for processing — do not upload sensitive videos unless you trust that service. 2) It uses a single API token (NEMO_TOKEN) for authorization; only provide that token if you trust the provider. If you don't have a token the skill will request an anonymous token from the same API and use it for the session. 3) SKILL.md mentions reading its own frontmatter and detecting install-paths and a possible local config directory (~/.config/nemovideo/) — ask the skill author to confirm whether the skill reads that directory and what it contains. 4) The skill's source/homepage is unknown and owner ID is opaque; if you need higher assurance, request a published homepage, source code, or vendor documentation before sending sensitive content. If you only need to test functionality, prefer using non-sensitive sample videos and revoke or rotate any token you provide after testing.

Getting Started

Ready when you are. Drop your video files here or describe what you want to make.

Try saying:

• "extract a 10-minute YouTube tutorial video into a 1080p MP4"
• "extract and download subtitles from this video as an SRT file"
• "downloading subtitles from videos for reuse or translation for content creators"

Getting Connected

Before handling any user request, establish a connection to the backend API. Show a brief status like "Connecting...".

If NEMO_TOKEN is in the environment, use it directly and create a session. Otherwise, acquire a free starter token:

• Generate a UUID as client identifier
• POST to https://mega-api-prod.nemovideo.ai/api/auth/anonymous-token with the X-Client-Id header
• The response includes a token with 100 free credits valid for 7 days — use it as NEMO_TOKEN

Then create a session by POSTing to https://mega-api-prod.nemovideo.ai/api/tasks/me/with-session/nemo_agent with Bearer authorization and body {"task_name":"project","language":"en"}. The session_id in the response is needed for all following requests.

Tell the user you're ready. Keep the technical details out of the chat.

Subtitle Downloader — Extract and Download Video Subtitles

Send me your video files and describe the result you want. The subtitle extraction download runs on remote GPU nodes — nothing to install on your machine.

A quick example: upload a 10-minute YouTube tutorial video, type "extract and download subtitles from this video as an SRT file", and you'll get a 1080p MP4 back in roughly 20-40 seconds. All rendering happens server-side.

Worth noting: shorter video clips produce subtitle files faster and with higher accuracy.

Matching Input to Actions

User prompts referencing subtitle downloader, aspect ratio, text overlays, or audio tracks get routed to the corresponding action via keyword and intent classification.

User says...	Action	Skip SSE?
"export" / "导出" / "download" / "send me the video"	→ §3.5 Export	✅
"credits" / "积分" / "balance" / "余额"	→ §3.3 Credits	✅
"status" / "状态" / "show tracks"	→ §3.4 State	✅
"upload" / "上传" / user sends file	→ §3.2 Upload	✅
Everything else (generate, edit, add BGM…)	→ §3.1 SSE	❌

Cloud Render Pipeline Details

Each export job queues on a cloud GPU node that composites video layers, applies platform-spec compression (H.264, up to 1080x1920), and returns a download URL within 30-90 seconds. The session token carries render job IDs, so closing the tab before completion orphans the job.

Skill attribution — read from this file's YAML frontmatter at runtime:

• X-Skill-Source: subtitle-downloader
• X-Skill-Version: from frontmatter version
• X-Skill-Platform: detect from install path (~/.clawhub/ → clawhub, ~/.cursor/skills/ → cursor, else unknown)

Include Authorization: Bearer <NEMO_TOKEN> and all attribution headers on every request — omitting them triggers a 402 on export.

API base: https://mega-api-prod.nemovideo.ai

Create session: POST /api/tasks/me/with-session/nemo_agent — body {"task_name":"project","language":"<lang>"} — returns task_id, session_id.

Send message (SSE): POST /run_sse — body {"app_name":"nemo_agent","user_id":"me","session_id":"<sid>","new_message":{"parts":[{"text":"<msg>"}]}} with Accept: text/event-stream. Max timeout: 15 minutes.

Upload: POST /api/upload-video/nemo_agent/me/<sid> — file: multipart -F "files=@/path", or URL: {"urls":["<url>"],"source_type":"url"}

Credits: GET /api/credits/balance/simple — returns available, frozen, total

Session state: GET /api/state/nemo_agent/me/<sid>/latest — key fields: data.state.draft, data.state.video_infos, data.state.generated_media

Export (free, no credits): POST /api/render/proxy/lambda — body {"id":"render_<ts>","sessionId":"<sid>","draft":<json>,"output":{"format":"mp4","quality":"high"}}. Poll GET /api/render/proxy/lambda/<id> every 30s until status = completed. Download URL at output.url.

Supported formats: mp4, mov, avi, webm, mkv, jpg, png, gif, webp, mp3, wav, m4a, aac.

SSE Event Handling

Event	Action
Text response	Apply GUI translation (§4), present to user
Tool call/result	Process internally, don't forward
heartbeat / empty data:	Keep waiting. Every 2 min: "⏳ Still working..."
Stream closes	Process final response

~30% of editing operations return no text in the SSE stream. When this happens: poll session state to verify the edit was applied, then summarize changes to the user.

Backend Response Translation

The backend assumes a GUI exists. Translate these into API actions:

Backend says	You do
"click [button]" / "点击"	Execute via API
"open [panel]" / "打开"	Query session state
"drag/drop" / "拖拽"	Send edit via SSE
"preview in timeline"	Show track summary
"Export button" / "导出"	Execute export workflow

Draft JSON uses short keys: t for tracks, tt for track type (0=video, 1=audio, 7=text), sg for segments, d for duration in ms, m for metadata.

Example timeline summary:

Timeline (3 tracks): 1. Video: city timelapse (0-10s) 2. BGM: Lo-fi (0-10s, 35%) 3. Title: "Urban Dreams" (0-3s)

Error Codes

• 0 — success, continue normally
• 1001 — token expired or invalid; re-acquire via /api/auth/anonymous-token
• 1002 — session not found; create a new one
• 2001 — out of credits; anonymous users get a registration link with ?bind=<id>, registered users top up
• 4001 — unsupported file type; show accepted formats
• 4002 — file too large; suggest compressing or trimming
• 400 — missing X-Client-Id; generate one and retry
• 402 — free plan export blocked; not a credit issue, subscription tier
• 429 — rate limited; wait 30s and retry once

Tips and Tricks

The backend processes faster when you're specific. Instead of "make it look better", try "extract and download subtitles from this video as an SRT file" — concrete instructions get better results.

Max file size is 500MB. Stick to MP4, MOV, AVI, WebM for the smoothest experience.

Export as MP4 for widest compatibility.

Common Workflows

Quick edit: Upload → "extract and download subtitles from this video as an SRT file" → Download MP4. Takes 20-40 seconds for a 30-second clip.

Batch style: Upload multiple files in one session. Process them one by one with different instructions. Each gets its own render.

Iterative: Start with a rough cut, preview the result, then refine. The session keeps your timeline state so you can keep tweaking.