My brother's 95 Ultra did it with my skinny 160lb butt on it, especially with my feet on the hiway pegs. He weighed ~275lbs (Ride Forever Free Ace) and said he never had a problem. I also rode an 08 low-mileage Ultra and swear that one would do it out of NOWHERE. Much worse and scarier than in that vid. I tried everything to prevent it, super-light touch on the bars, being as smooth as possible, shifting weight forward/aft. Nothing seemed to help prevent it, other than just going slower to begin with. I found that I could stop it fairly quickly by stabbing the rear brake. That seemed to jolt it back to civility.
I can get my 09 Classic to do it, but I really have to push it (20-30mph over the 08) to make it do so. I do 35mph curves at 50mph no prob on the 09.
On the '09, by the time it starts, it seems that it's much closer to 'the limits'.
It also damps out much quicker.