I had this Bad URL message from youtube and spent some time to find out the cause :) So… in line 236 of youtube-channel.php you use short open tag "<?"
src="http://www.youtube.com/embed/<? echo $yt_url."?enablejsapi=1";....
but my hosting has directive short_open_tag=off by default in php.ini. Temporary I replaced "<?" with "<?php" and problem has been solved :) Other solution is to switch the directive to On but it can be impossible on some hosting servers.