SEMRush posted a screen shot on Twitter of Google showing a query expansion feature, like the people also ask feature, for video carousels. It is titled "related videos" and shows you different queries you can try in Google to show more related videos in the Google search results.
Here is the screen shot:
Again, just another form of query expansion to get searchers to think differently about their previous query and to get Google to get searchers to try another search triggering potentially more ads.
Forum discussion at Twitter.