Just installed MediaElement.js and didn't find anything on this topic:
My poster images all are in an offset position from the player. This results in a "ghostery appearence" of the image (double display).
Better have a look for yourself:
http://www.gido-griese.de/portfolio/imagefilm/
How can I get them on the same position?
Why are they actually offset?
PS: Used "Degradable HTML5 audio and video" before and this did not occur...
http://wordpress.org/extend/plugins/media-element-html5-video-and-audio-player/