For a couple weeks now playback on Safari would just stop every few minutes and reset the playback position.
Sometimes it would mark the media as played, sometimes unplayed - I couldn't detect a pattern.
Same behavior in beta and stable.
It didn't happen in Firefox so I assumed safari was the problem.
Discovered playback in a Safari "Private Window" worked so I thought okay state must be corrupted.
Deleted cookies, local storage - nothing made a difference.
Digging