YTPlayer jQuery plugin let’s you play YouTube videos in background with HTML5 video player. An open source jQuery component to easily build your custom YouTube® player by making use of both HTML5 and YouTube API.

Now, you can also use YTplayer in your WordPress blog. mb.YTPlayer for background videos is what a video player plugin for WordPress through which you can play YouTube videos in background of posts/pages.

YTPlayer - Plays YouTube Videos in Background with HTML5 Video Player

Check out the Demo here.