The eccentricity is coming from inside the freewheel..not exactly sure of the names of the internal parts and it probalby doesn't matter anyway. ACS freewheels have the same problem, only worse than the WI industries freewheel in the video. I have never noticed it in a Shimano freewheel, using the same hub, but am not saying that all Shimano freewheels are perfect.
None of this really effects the performance of the freewheel anyway as long as the eccentricity isn't too severe. But if I'm going to spend that much on a freewheel it had better be perfect.

My main gripe with WI freewheels is not that they are poor quality (they are not) but just that they are overkill. The internals of a basic freewheel are really quite simple and easy to overhaul if necessary. I have never had a cheap freewheel fail, and I've ridden them in some pretty ****ty weather, and I have never overhauled a single freewheel. There isn't really a need for sealed bearings..the bearings only spin when coasting anyway..they don't do anything when under a load. In my experience the teeth shark-fin before the freewheel fails...even if the bearings last for infinity, the cog, just like any other cog, will eventually need to be replaced after several thousand miles. Any freewheel should easily last that long.

The WI trials freewheel on the other hand, may have other advantages due to the greater number of engagement points...giving it a tendency to engage faster, which is notable when riding with a really low gear. On a high-geared road SS, I don't think the number of pawls really makes much of a difference.