Youtube and dailymotion videos do not embed properly, they show errors and broken links for the videos. I haven't tried the other video sites.

Same video links play fine here but not on this site.
There are some bizarre issues with the parser (relating to HTML sanitization) that I've noticed but haven't tested extensively yet, so this could be part of it.

<span style="font-weight: bold;" class="mycode_b">an example</span> - MyBB lead designer and team member since 2006
They work on the newreply/newthread page inside the editor but they break once you post it.