I have been fighting to get webcam work in Skype under Linux for few days. At first, it didn't work at all. Later, I figure out I need to put
export LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so
before using Skype.
But, this didn't solve all the problem.
So, I kept searching and final found some weird X Window error:
X Error, request 132, minor 18, error code 8 BadMatch (invalid parameter attributes)
And found the solution here:
http://forum.skype.com/index.php?showtopic=411441&st=60&p=2124231&#entry2124231
export XLIB_SKIP_ARGB_VISUALS=1