Create a dynamic gallery multiple widget(works as shortcode too), with thumbnails of each post with youtube/vimeo(beta) videos displayed on the content linked to the post single. Checks all you video posts, but you can filter them by category and choose the number of posts.
Based on
Media Library Gallery 1.0.2 (http://www.cybwarrior.com/media-library-gallery/) by Raphael Verchere(http://www.cybwarrior.com)
Video Thumbnails 1.0.7(http://sutherlandboswell.com/2010/11/wordpress-video-thumbnails/) by Sutherland Boswell(http://sutherlandboswell.com)
and
Simple Video Embedder(http://www.press75.com/the-simple-video-embedder-wordpress-plugin/) by James Lao(http://jameslao.com/)
Special thanks to Felipe Caroé http://www.felipecaroe.com/ for suggesting the name!
Arbitrary section
This Plugin supports YouTube and Vimeo(beta)
If you decide to use iframe and embed object, please use the html code insert on the post
The plugin works better when urls are pasted on the post editor
This readme file were validated at https://wordpress.org/extend/plugins/about/validator/
Screenshots
Configuring the widget.
See it working on http://www.felipecaroe.com/galeriavideos/