My favorite Fred move ever was against the Giants in 2011, when he was breaking away on an 80 yard TD, and the DB was just about to catch him as both ran full-speed toward the end zone. Out of nowhere and maintaining full forward speed, Fred makes a little shift to the left at a low angle, which is enough to send the DB off into no-man's land while Fred scores an easy TD. Magical old-man powers right there.
There's no name for it that I know of, but Fred had that sudden open-field change of direction at full gallop that made it so hard to close on him.