If you try watching a video recording on twitch etc. while it’s still ‘live’, mpv/youtube-dl will play the live video instead of starting from the beginning.
The fix is straightforward: By appending
?t=0m you can force it to start at the beginning:
This is also useful for a second purpose: seeking. Normally, by trying to seek a live stream like this in mpv you will end up buffering and downloading forever. (I’m not exactly sure what’s going on since the mpv cache is so opaque, but I have to imagine it’s actually trying to download all the data you skipped past)
By changing it to e.g.
?t=20m you can seek to 20 minutes in the stream.