I agree savoia. He was taxiing quickly, and may have been a little light on the wheels as he tried to straighten out from the turn? It looked like their was some significant lean to the left as he turned the corner then as the aircraft sprung back the shimmy started.
Only time I've had nose wheel shimmy was taxiing too quickly, and too light on the wheels as I touched down with a little run on speed (maybe 10knots).
Aser: what you describe is fair enough. However I think Savoia's point was the way in which this wheel shimmy was induced (perhaps hurried taxiing); not to say that all shimmy is a result of bad taxi technique.