Thanks Dynamite and Wiiksie. And Thants too!
The DivX page looks great, but I know from experience that not many people have the player so would rather steer clear of this if possible.
The QuickTime options looks okay so I'll try that. I thought I read somewhere ages ago that Google were re-coding all the YouTube videos from Flash into MP4, and that the latest flash player would play MP4 files? I'll have to give that a go.
My previous effort was to embed a video, but that meant all 70mb (or whatever size it was) had to be downloaded first which wasn't ideal!
Thanks,
Ste