Youtube videos won't play on IOS (tested on iPad and iPhone 3gs).
Further investigation revealed that modestbranding=1 was the cause. According to http://code.google.com/apis/youtube/player_parameters.html
"This parameter is supported in the AS3 embedded player and in IFrame embeds that load the AS3 player. (IFrame embeds could also load the HTML5 player.)"
It does not state that it breaks the HTML5 player, but at the moment it seems like it does.
Could you please make this an option in the plugin admin, so people can disable it?
As a temporary fix I deleted '&modestbranding=1' from line 244 of generate-embed-code.php