VK video downloader: separate paths for video and for music

VK video and VK music are not the same job

1. Two separate APIs

VK video comes from the stream manifest on the playback page, while music goes through a completely separate audio endpoint, and the playback address it returns usually carries an expiring signature and needs a signed-in session.

So you end up in this situation: yt-dlp and Cobalt.tools can download VK video, but for music they either have no support or need extra configuration. To save music off VK, a dedicated extension is one of the few routes that works.

2. Music needs you signed in

The VK music library has licensing and regional restrictions, and anonymous access basically never gets you a playback address. An extension runs inside the session you are already signed in to, so it can fetch whatever you were already entitled to play - its ceiling is exactly your account's permissions.

3. Bulk playlist grabs trip rate limiting easily

A playlist's track list is delivered by the API in one go, so completeness is better than with anything that relies on scrolling. With a long playlist, though, back-to-back requests trip VK's rate limiting easily, which shows up as a run that dies partway. Split it into batches and raise the interval.

About music copyright

Content in the VK music library belongs to labels and artists; VK only provides playback. Downloading a track to listen to yourself may fall inside private copying, but redistributing it, uploading it elsewhere or using it commercially is all infringement. The line here is tighter than it is for video.