Can I use this with my AppleTV to have good sound in my lounge when watching TV?
Depends on how these things connect. If Bluetooth, then probably yes. If Wifi only, then the TV will have to transmit audio via AirPlay. That will mean a change in how the TV works. I believe right now it's only capable of receiving an AirPlay stream, not sending one. And it will likely require an TV 5 in order to have enough processing power to stream full bandwidth wifi audio via AirPlay, and communicate with the speaker to approximate distance from the screen to maintain proper sync with the picture; in addition to streaming video from the web.