You know, glad you pushed me on this one. Check it out:
http://www.youtube.com/watch?v=txqiwrbYGrs&hd=1
It's vbcode so you do:
'open bracket youtube closebracket uniqueIDfromyoutube openbracket forward-slash youtube closebracket'
I'll get some other sites working if I can and make a post about this.
As for the text size, click on the Shoutbox header, and from there I think you can change it for yourself