From the help section
The current policy is to only allow one Network stream per login. If you logout of the device you are viewing on, you can then stream on a different device.
But I was able to get two different streams going at the same time on my desktop and iphone, dont know if its just...
But now that I actually trying it out, im able to stream from my desktop and iphone at the same time, give me a minute and ill see if i can get my ps3 going.
From the help section
The current policy is to only allow one Network stream per login. If you logout of the device you are viewing on, you can then stream on a different device.