Why sensor size is more important than the sheer number of megapixels

This video explains the benefits of larger camera sensors such as the 2/3inch EXR-CMOS II in our compact X20 and XQ1 cameras and the APS-C sized sensor used in our X100S and Compact System Cameras.

http://www.youtube.com/watch?v=NKVrfMeqWM0