final cut pro masking

I am currently working on a video project that needs to have a video that includes a tv set and I need to put a differant video on the television. Is there a way of cutting out the tv screen to reveal the layer below as you would in photoshop??

You can do it in Final Cut, but would be faster to do it in Motion. Just right click and choose send to motion. This will take your video, create a motion project with the video embedded in the project. Import and scale the new video for the TV, then mask it to match the TV Frame. Save and its updated in Final Cut.