This is really weird but I posted three vimeo videos to my site via Vodpod and viewed them online without editing in WP and aside from the formatting they looked fine.
But when I edited them in WP in source mode, all the code vanished! Well most of it.
Here's the original vimeo code for one of the videos:
After looking at it in source mode, when I switched back to display view the first section of code had gone!
Is it the iframe tag that's doing it? If so, how do I alter it?