My first sprocket had only one flange on it. It wore out in about 3,000 miles. The second one had a flange and it lasted about 9,000 miles before eating itself. The third one has a flange but its days are numbered. I sent the second one to SuperMax where the aluminum teeth were machined off and relined with a neoprene set with only one flange.
If the tracking and tension are done right having two flanges should not be necessary. The bevel box has two so it won't drift too far.
On the video I noticed a bit of chirping from the belt on the sprocket. I'd want to ease up on the tension of the belt. Morgan states that you should only be able to twist the belt 45 degrees but 90 will do. As long as it doesn't ratchet (skip a tooth) then it's tight enough.
