I bought my first webcam a couple weeks ago. A Logitech C310. Very inexpensive, but will do 720p at 30 fps. I installed guvcview, plugged the cam into a usb3 port (have loads of them-it's a usb2 cam) and it worked first time recording a vid of me looking at it and waving to test motion. I did not hear any sound from the playback and haven't checked if sound is not working or I was just too quiet. Vid quality is reasonable at 720p for a device I got for $24. I bet you would want something more capable than a C310.
If you are looking to make a professional quality video you probably want something a whole lot more pro than a webcam. The sensors in these things are tiny. A good DSLR camera is capable of video with much better quality. The sensors are about 50 times larger.
Logitech also makes a C510 and C910 ( I think ) The 910 is capable of 1080p, but it won't be the same as watching any professionally recorded 1080p movie.
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