This setting , when turned on, will send a constant feed to the connected remotes. If the connected remotes have show live feed turned on they will see whats always happening on the running booth.
Using this setting will increase the load on the device. It will use a lot more CPU and Memory and therefore will also reduce battery life. So just keep that in mind:)
PG Booth, the DIY Photo Booth App for iPhone, iPad, & Apple TV :p