I see, I think I tried that before but thought it didn't work because it doesn't show up in VLC. For mkv's the audio tracks names and language are displayed in the Audio track selection menu, but tagging an mp4 like this doesn't affect VLC, it just shows "Track 1" etc. The only thing VLC displays are the tracks' language, but I guess it's an issue with VLC. Does both Track name and language show up in AppleTV or where do you see it?