That's probably the oddest thing I've heard from Microsoft so far. If you're on Windows, you might have better luck playing .mov files like that one using VLC Media Player. But if not, I've reuploaded the video to bunkr. Here's the link:
https://cdn10.bunkr.ru/Slippery-when-wet-52aL3KV8.mov Just checked, and it's black on bunkr too. I'll try re-encoding it later today into mp4 or some other format to see if that fixes the issue of it being black on these sites.