Video playback variable speed

I observe a strange behaviour in the latest versions of AppleTV Black. The sound and video is inn sync but the video looks as if it needs to “catch up”. It is a bit to fast, it jumps a little bit and continues. This is generally with an interval with 2 seconds.

I am in Europe where the framerate is generally 25 fps. The videos i play are usually of American origin and are 23.97 fps. The video type I play the most is xvid.

I have observed this behaviour when I upgraded my AppleTV to the latest firmware 4.4.4. I do not know if the AppleTV firmware can have any impact on this. I tried downgrading but it seems that this is not possible.

Is there anybody else who has seen this effect? What can be done about it?