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I went to it with my iPad and it didnt load, but if the page enables AirPlay, you should be able to stream from your iDevice to atv2 from a webpage.
 
Well, it is not working on my iPad neither. I meant on my iMac... I play the stream on my iMac...
 
I do not think it is possible. Maybe with a jailbreak, but I am not sure what jailbreaking your atv allows for.
 
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