As much as I hate FB I have to admit they're very good at finding ways to keep people on the platform. From the video in the post it seems Watch will provide a better UX than YouTube, especially for comments.
Tv.Youtube is a bit better... but I have faith they will step up as it continues to dominate.
Did a poll of my little cousins at a wedding, they would all rather have a Youtube Red subscription than Spotify or Netflix.