I do not think the user particularly cares whether it was an intentional feature or an unfortunate byproduct of features and bugs when they open a laptop in a classroom or a meeting and it starts blaring the music they listened to before closing it.
It's like being literally unable to dog
Opening a laptop, even if the last activity was blaring obnoxious carnival music, should _allow_, not _demand_ the user to resume their last function - which was explicitly to _pause_ the laptop, by closing the lid.
If I close the lid, I am done with the computer and video; it is obvious that I am done right now - the OS/browser would be alerted of LidDown, and I would expect the OS to tell the browser to Pause (via some new javascript media API that I am sure exists), pagefile ram if possible/needed, and dump all console.logs to a temp directory, in case restarting from hibernation goes awry.
If I open the lid, I am attempting to use the computer. The previous quest can be pertinent or moot; but it would be oddly assumptive (against the ethos of general computing) to _automagically_ resume (especially a paused) playback just from first button press - at least give me the option to explore, format, or rename the thing.
It has never happened before...
Windows 7 with Youtube can figure out - even with hibernation breaking audio/bluetooth on windows - then surely the most expensive company and OS 15 years later has made an inkling of progress (if that was ever their intention)