MyBB Community Forums

Peharps is it obvious, but I spent a few time to understand why videos didn't work anymore on my forum. And I found my stupidity !

I had change it from http to https, so the youtube url (in the video_youtube_embed template) must have the https scheme.
I think it's the same for other video hosters.

So, if videos don't display, verify this.

It's best to use the same scheme that your forum uses, to avoid mixed content issues/warnings.
So if your forum uses HTTPS, all video embeds should use HTTPS as well.

Perhaps using "://..." instead of "http://..." might be a more generic solution, though I'm not sure about compatibility with the former.