GitHub is deprecated as a documentation source. See: Twitch Developer site launch - #4 by george
The reference to video-playback is included in error on https://github.com/justintv/Twitch-API/tree/master/PubSub the only part that “appears” to be documented is the topic name itself, none of it’s message responses is listed.
PubSub Documented: https://github.com/justintv/Twitch-API/tree/master/PubSub
Bits Documented: https://github.com/justintv/Twitch-API/blob/master/PubSub/bits.md
Whispers Documented: https://github.com/justintv/Twitch-API/blob/master/PubSub/whispers.md
VidoePlayback Documented: None.
All of the above GitHub documentation links are invalid and no longer supported and are superseeded by dev.twitch.tv github means nothing
PubSub documentation: PubSub | Twitch Developers
Bits Documentation: https://dev.twitch.tv/docs/v5/guides/PubSub/bits/
Whispers Documentation: https://dev.twitch.tv/docs/v5/guides/PubSub/whispers/
VideoPlayback Documentation: none.
I hope this clears it up for you?
The presence systems is not the video-playback topic, and is also undocumeted and thus unsupported.
DevSuccess is a WHOLE different department to the Twitch Partnership department, which deals with ability for users to Subscribe to a channel.