Embedding YouTube videos using the "Insert Flash" button doesn't seem to be working. The page makes room for the video, but all that shows up is the link text.
I don't think that feature's worked for years.
It's a little borked now but the workaround is to paste the link directly in like so:
https://www.youtube.com/watch?v=8aICVBnO4Usand manually remove the "s" from "https" so it appears: