Sorry I didn't get back to you sooner , I was in the shop.
I took a closer look at my saw(basically all the same) . The top wheel is riding bearing on a stationary shaft. If the shaft were bent ,it would cause missalignment not wobble. If the bearing was shot it would cause vibration , not wobble. I'm sure that the top wheel is warped.
On the bright side , it should be quick easy fix once you get the part. I would get a new bearing while you are replacing the wheel, if it's seen much use. This way you won't get it back together only to find out that the bearing is shot as well,or will be a month later.The bearing should only be about $20-25 . I have no Idea what the wheel would cost. When you order the wheel , make sure it comes with the rubber tire on it. It should, but would suck to wait for a package that didn't have all the parts.
Without being there in person ,I could be missing something, but from the video , it seems fairly clear. Never hurts to get a second opinion before you order any parts.
You still don't seem too sure of what you are supposed to be looking at in the vid. I was watching the aluminum top wheel (barely visible behind the blade ) in relation to the back bearing (that gives you a fixed referance to observe deviation)