I've also tested both files.
It does not help in Ios5, Airvideo beta6
In both cases it stops after 4 seconds.
Did you receive any feedback from the airvideo mods ?
I'm a registered owner of Airvideo, I purchased the app.
And I'm sure most people here have purchased the app, so we could all send them an e-mail.
Maybe this just needs to get some more attention with them ?