I've been wondering what the purpose of those super-long ads is for some time, but now it suddenly occurred to me: they're for unattended youtube players.

Plenty of shops, waiting rooms, lounges, bars, etc have a TV which is simply tuned to a youtube playlist. Whoever is issuing those ads is counting on that the operators of those TV's for whatever reason (either because they don't care, don't notice, or don't have access to the controls) don't skip them.