I couldn't get the video to work,so I'm not sure what their claiming.
RE bump steer; In stock form with a stock alignment, most mopars only have .125 inches of bump steer at the far ends of suspension extension. Within the normal range of an inch up and an inch down, there is actually very little change in toe at all. Also, bump steer is inherent with any strut rod suspension. It is inevitible because the strut rods length causes it to move in a conflicting arc to the control arms. The further the suspension movement, the greater the change. The only way to truly eliminate bump steer is to use control arms the have triangulated mounting points in the same longitudal plane. Even the Hotchkiss design tie rod mounting points will have some bump steer at the extremes of travel. Granted, it is probably less than stock, but it will still have some. One thing most people tend to overlook as well is that bump steer can actually be used to your advantage in a mopar. As the suspension toes out, it actually increases the ackerman effect on the car which can create more favorable slip angles for the tires in tight cornering.
RE camber gain; Mopars naturally increase negative camber as the suspension compresses. This is in sharp contrast to a number of popular muscle era chevys that do the opposite. As a car corners and the body rolls, the front outside tire compresses, in order to maintain good contact, the tire must gain more negative camber is it travels to balance the contact patch against the body roll. By shortening the upper control arm, as Hotchkiss did with their odd looking mounting blocks, you increase this negative camber gain, considerably. I'm actually surprised no one has done this mod before. Coincidently, you can gain the same effect by installing taller spindles, aka the late B or FJM style, which also will net you a 3# weight loss per side.
I also noticed that by altering the upper control arm mounting points, they eliminated the anti-dive geometry. This may produce some exaggarated up and down movement of the nose under braking unless you are running some pretty beefy torsion bars. Most race vehicles don't have anti-dive built in to them because they have such large springs rates. Most stock vehicles have it to balance out the dive against the softer spring rates that most prefer for the street.
For hollow sway bars, check out Speedway Engineering's web site. They will require some fabrication to make mount and attach, but they are out there. Unlike the Hotchkiss design, SE's hollow bars can be easily swapped and the end links altered to produce the best balance and optimal rates when combined with each particular t-bar and leaf spring combo. But, you'll need to do the math to figure it all out.