Hi,
since a week I have a weird bug.
After watching a video, clicking back to YT (Logo) in background an ad starting automatically - no visual on the Youtube start page.
First I though I hovered over a video (like preview), but if I do so, it stops (the ads in background).
One ad played, after that, silence. 
This is happening very often a day (in my case).
Very strange bug, since I often see “Experiencing interruptions? Find out why” which delays every video start from 3 to 15 seconds.