I feel like auto-play ads make sense on youtube because youtube is a video service and you go in expecting a video anyway. It's like a TV commercial.
I get super pissed by auto-play ads on non-video websites, but when it's in front of a video such as on youtube I find it only a minor annoyance.
[EDIT: I don't know if there are auto-play ads in the sidebar on desktop, I use adblock on desktop so I only see those video ads on the mobile version, which doesn't have anywhere else to put ads]
There's no shock of audio but it's still stopping you from getting to the content. It's just as bad as full-page interstitials. (By the way, does anyone else get unreasonably mad that the button to leave such an ad usually says "skip" even when the ad was already shown and stays up indefinitely?)
I get super pissed by auto-play ads on non-video websites, but when it's in front of a video such as on youtube I find it only a minor annoyance.
[EDIT: I don't know if there are auto-play ads in the sidebar on desktop, I use adblock on desktop so I only see those video ads on the mobile version, which doesn't have anywhere else to put ads]