One measure of the video quality of different cameras is whether the camera is 1-chip or 3-chip.
The 1-chip camera uses a single computer chip to process the colors the camera sees. The more expensive professional 3-chip camera has three separate computer chips. Each chip processes a separate primary color - red, green or blue. Because of this, the video quality is much better.
Professioinal cameras are often labeled as 3-CCD or 3-CMOS (CCD stands for "Charge Coupled Device, and CMOS stands for "complementary metal oxide semiconductor."