Specifically, certain video-streaming apps such as those from satellite services (DirecTV) and premium cable channels (HBO Go) are perfectly happy to let you watch their content on your iOS device. Want to project it over AirPlay or via a cable attached to your TV? Oh no. You can watch this stuff on your TV. You can watch it on your computer. You can watch it on your iOS device. But try to project it from one device to another, and you've enraged the "we're more interested in our arcane license agreements than customer convenience" gods. UnrestrictPremium2 is designed to block those "oh, no you don't" flags that prevent this kind of convenience. It doesn't always work, because the media conglomerates routinely update their apps to lock down their content. But when it does work, it's wonderful.
Jailbreaks for all?
In August 2010 I considered the pros and cons of jailbreaking your iPhone, and my feelings on the subject have changed little in two and a half years. As I've described, doing it has clear benefits for me. But clearly this is edge-case use, and jailbreaking isn't for everyone. When you jailbreak your iOS device, you void your Apple warranty, you have to be more careful about the apps you install, and you risk a less stable device.
My most fervent hope is that iOS (and media license agreements) will evolve to the point where I find jailbreaking entirely unnecessary. Until that time comes, however, I'm a jailbreaker.