I spent a big part of the weekend trying to get my own code to grab a still image from my web cam. In the end I had a complete failure, then I realized I had fallen into a trap that could happen to others.
The USB web cam driver that was originally published as being for CE 4.2, 5.0 and 6.0 uses a set of IOCTL commands to interface with it. The USB cam driver for 6.0 is a DSHOW camera interface and the IOCTL commands will compile and run. But they will always fail.
So don't try to use the CAMTest2/3 code you can find on the net with this driver (like I did :)
The shared source sample does use the DSHOW interfaces so it will work. Now all I have to do is figure out just how to use all that dshow stuff.