It looks like YouTube is testing new search results by highlighting keywords attached to a video in hashtag format.
Unfortunately, the audio is a bit messed up on this because the memory on my computer was pretty full when I recorded it. But I wanted to risk that in order to at least capture what YouTube’s new layout looks like. Sure enough, after recording this I went back to YouTube and it’s SERPS were back to the old format. They clearly are testing out this new layout. YouTube Topics Search found at YouTube from estrategy.