YouTube is testing picture-in-picture ads for live streams.

TikTok has been implementing mid-roll ads. While watching longer videos, over a minute, some users are being served ads during the videos, typically towards the end. In these cases, a pop-up appears at the top right of the video with a countdown for the ad to start. The ad then starts playing with the option for users to skip it. After skipping or letting the ad play through, the video continues.