OK Now working on Firefox as well (if anyone is interested we needed to allow the MIME type .webm on the server).
Videos checked in Firefox, Opera, Safari, all seem fine. Serving video via HTML5 to allow smartphone and tablets to access them means producing in four separate formats, hopefully soon they will standardise!!
If your viewing over 3G the videos probably will hang as your downloading 16meg of video files, best to let them load at least half way and then play. We may add them to YouTube, but the quality once they compress it is never as good.