Should I use HTML? Test:
(Unsupported https://www.youtube.com/watch?v=FGSdP_bHL7c)
If so, are dangerous tags escaped? Test:
Will I be able to remove this test post or at least edit it? Let's see.
Added:
Fortunately, HTML is escaped. And somebody has just pointed out that all I have to do is to insert a link to youtube video. It will be included properly automatically. Test: