video.js plugin display size on mobiles?

hi,

I’m just setting up video.js on a new website managed in WP, and I’m using the video.js plugin for some embedded video clips. It is working OK on desktops but on mobiles (Android/iPhone) I see all clips at their original dimensions of 720×576 which are obviously much too large for small devices. Is there a way of forcing a smaller clip (say 320×256) to render on mobiles?

sample page: http://www.edsirrs.com/test4r

any ideas?
cheers phil

http://ww.wp.xz.cn/extend/plugins/videojs-html5-video-player-for-wordpress/