I have just discovered this issue. VLC works but is a poor workaround. I will certainly advise anyone to avoid buying the Airplay device.
In my view Airplay is a gimmick, mirroring that is.
I could not imagine buying AppleTV for Airplay mirroring alone, unless maybe delivering a presentation from an iPad or similar.
It is quite network dependednt and for the average user there are far too many ways this can fall down.
Immature technology which will improve - I'd imagine teh other screen sharing technologies out there are of similarly mixed experience too.
AppleTV was and still is a great device for media playback - the problem is the plethora of other media streamers and competition to provide a diverse range of features for everyone rather than doing a core job very well which is what AppleTv 1 did.
It;s the same with TVs, amps and so forth.
I bought a new surround receiver the other day - there are so many little features to compare it's easy to find one device that does something better than another in certain but not all areas.