So, it used to be that the list of stuff in http://www.livejournal.com/support/faqbrowse.bml?faqid=268&view=full included the methods for embedding stuff using HTML. This was handy because you generally could use the same thing for comments-- want to put a YouTube video in the comments and have a YouTube war? Go for it! Just paste in the HTML, etc.
Well, FAQ 268 is now nice and short, since there exists the handy whitelisting "embed media" tool.
Unfortunately for many of our users, they still want to know whether/how they can embed various things in A) comments and B) their profiles. And other than knowing that YouTube videos can still be inserted into comments, I have no clue what's available.
I don't know whether this should/could/would be a new subsection of FAQ 268, or a whole new FAQ by itself, or what... but while it's easy to find out that answer for static images (hello, FAQ 6!), there isn't anything that answers it for the other media thingees.
[#include generic suggestion/request for entry-like RTE-ish comments reply box here. hah hah hah.]