This post is a follow-up for anyone interested in using the Universal I, 2, or 3....if there is any interest. If not, ignore, since it's not especially interesting or applicable to modern rotary vises. I have a HMH TRV, which is in almost all respects a better true rotary, but I like the Universal 2 because it's old technology which I think is pretty good for its day. I don't know why it didn't catch on. Except maybe because there's less access to the tail of the fly unless you reposition the hook. One advantage is you don't twist the thread when winding it if you do it right.
After using the vise for a few weeks and then reading the manual referenced above, I realized the cleaning instructions on the video on the linked video isn't exactly right. I followed the instructions for cleaning, but found the video displayed the final position of the jaws 180 degrees from brochure so it's not on the same axis as the jaws. You can;t rotate the jaws as the vise was originally designed. Otherwise, essentially, you're tying on a stationary vise that is capable of being rotated, but not a true rotary.
You can control the position of the fly to examine it or for whatever reason, if without the O ring you apply pressure on the chuck with your off-hand to stop the rotation. I like the true-rotary, free spinning, hook-in-line with the axis of the jaws because you can really spin thread or body material on (like on a streamer) and there will be no wobble. Kinda like a Nor-vise in action. The video is good for cleaning and lubricating, but if you study the instructional brochure, you'll see how to properly place the hook so you can get more advantages of the true rotating vise.
If you watch the video to the end, he ties a jig, which is fine, but I see no advantages of using a rotary vise in this situation...it's like tying the jig on a stationary vise, which requires little or no movement of the jig. But if you tie a streamer and want to wind thread and material (dubbing or yarn or ribbing) you'll be more satisfied with the free-spinning jaws.