I was talking about the main site. I believe you originally selected your picture through Gravatar. Just go back there and change your pic. Or maybe you can just log out of Gravatar. I'm not fully sure how this works but you can basically change everything yourself.
A major forum upgrade was installed this week. It fixed a long list of bugs and improved its looks and usability. Also, you will now find profile posts on the sidebar of forums. With this increased visibility, an already existing forum rule will be enforced for profile posts:
Sorry for answering your original request a year later - I thought this was resolved.
According to the forum software help files, you can currently only embed videos from these sites: