I think the issues when watching YT maybe be due to YT still using Flash by default unless you opt-in for HTML5 at http://youtube.com/html5 ? I could be mistaken there, but it seems like the embeds show HTML5 by default but the main site still doesn't.

Anyways I'm super glad you like it, please give me a holler (contact info in profile) if you have any feedback or annoying issues.