I've a logitech webcam
➜ ~ lsusb | grep cam Bus 002 Device 006: ID 046d:0825 Logitech, Inc. Webcam C270
It works with Cheese and used to work with google hangouts. Now with google hangouts I get many flickering horizontal lines, that slowly disappear to white. Occasionally if I wait a few minutes it will start working correctly and I'll see the video from the webcam displayed on screen. I don't have enough reputation to post an image, but here's a link to google hangouts video error gif.
Any suggests about how to go about debugging this welcome.
Edit: Have not resolved issue with logitech, but did buy another camera and that is working fine.
➜ ~ lsusb | grep -i cam Bus 002 Device 015: ID 045e:0779 Microsoft Corp. LifeCam HD-3000