Ya i tried it in 2 versions of miui. One based on 2.3.3 and a later version based on 2.3.4
Worked fine in both but would force close if you press the audio/video icon on the usernames in the conversation window (workaround would be to open a message with them and hit menu and start audio/video chat with them in there) and if you switched to rear camera.
Otherwise, the video and audio came in fine. It would pause the conversation if you switched to wifi to 3g or vice versa and continue once your connection is connected.