Noticed this started while continuing to update my GOTY 2019 list. Started within the last week or maybe two weeks? It just leaves a big empty area where the video should be. Used to work fine of course, have had some videos in my lists for a few years. They were working fine on this one as well until recently as mentioned.
https://www.giantbomb.com/profile/seikenfreak/lists/game-of-the-year-2019-users-choice/365097/ for an example. I'm using Firefox 71.0 (64-bit). Tried it in Chrome as well and no luck. Tried deleting the video from the list, saving, then re-embedding the video. Still just an empty grey area.