Usually the USB jack is there for either a) a software upgrade port, or b) for portable thumbdrives, used to display still JPEGs or some music files. Very very few TVs will have the sophistication to play back video over USB, and your manual will be specific as to which formats are playable. USB is low speed and low res.
If you're dealing with a camcorder that has USB, look elsewhere for a good connection. Normally you'll have a composite, Firewire or mini-HDMI jack to port video from the camcorder.