I think is very annoying this thing called Annotations in Youtube. It gets in the middle of the content, the video, appears and disappears, if you want to pause the video by clicking on it and you click on a annotation, the video changes, etc... and usually it does not contain anything useful, to be honest.

A way to deactivate this option go to the URL: https://www.youtube.com/account_playback and disable the checkbox " Show annotations, channel promotions and interactive cards on videos " as easy as that.