Hello, and welcome to Just Answer, I'm happy to help you here.

What your experiencing is one of the safety features of the Apple iPhone, in that it won't share its video content through the USB port on a TV. This is a design function by Apple.

What you'll need to do to accomplish what your after is to either purchase and Apple video cable, which will plug into your iPhone and turn its docking connector into video connects.

Or, a more exciting way, would be to purchase an Apple TV and use the Airplay function to wirelessly stream it to your TV by linking the devices together.

Below is a link to the specific Apple cable you'll need. If you would like to go into the Apple TV connection in more detail just let me know.

Digital AV Adapter Link

You will still need an HDMI cable, but you may already have one of these laying around.

If you have any other questions just let me know. If you found this information helpful then select the ACCEPT button.

Thanks.