I have inserted a you tube video into a K2 Content item.  I added it using the video provider tab and entering the video ID. The video plays fine in the preview section however it just sits there and trys to load on the website.

Here in the main module position -tab 3 - velocause.org/

Joomla 1.5.21
AllVideos (by JoomlaWorks) 3.3

Thanks,