While going over the ximeraManuals repo during the audit I found the following:
It appears that the youtube command has been broken. A very cursory look suggests that the config where we changed it to xmyoutube may have broken or forgotten some code somewhere and caused this. To be clear, I think xmyoutube is a good idea, it just needs to be tweaked, maybe it is missing the v= or something else about the embed is busted.
Found during Ximera Audit