I have been using Express Animate for a few months (v2.03) and recently installed version 3, and then immediately experienced the same problem as JohnySK: video saves as sound with no picture. If I try to open the file in Express Animate I get "File format not recognised" which is a bit ironic. I tried saving in different formats with the same result.
This has nothing to do with disc space or anything like that, I uninstalled and reverted to the earlier version and now video - even projects created in version 3 - saves as it should. Plus, it doesn't change all the text to Arial 20 when I Undo but that's another story...