Thumbnail not working

Hi there,

I’m using the Video Thumnails plugin together with Gravity Forms to create user generated video posts. When users paste the video url into the form and submits it, it’s inserted into a iframe embed code and shown as a post.

This works fine, however – when using a url containing the playlist ID the video works, bu I seem to not get a thumbnail.

Any ideas why this could be?

http://ww.wp.xz.cn/extend/plugins/video-thumbnails/