Yup, the film Auto-Film feature does this to me too. I have yet to be fully disco'd because I'm quick enough to get out of that menu, but a squady got kicked because of it.
If you notice, when on that save menu, the entire game comes to a stop behind it. You don't see that you landed kills, and the animations and text buffer stop moving. After a few seconds, I lose UDP and it switches to TCP, however if I am fast enough, that doesn't happen. I blame the fact that it stops the game in the background, not sure what exactly would cause/fix that though.