Well, I'm using an old NTSC camera, and you need to run it thru a capture card for v4l2 to understand what it sees. There are various settings, like NTSC or PAL(Europe and S. America), etc. The TV cards also need to have a setting to tell them they are receiving a camera input (composite video) and not a TV signal. It's all going out of date, as the newer pure digital cameras take over. You can look at ztk-v4l-video-bloger/recorder to see how you need to use v4lctl to initialize old cameras. You can also start up xawtv, and look at the settings to see what your card/camera can do.

I have an el-cheapo digital usb webcam that I will test later. I think everything is going digital/usb now.