BTW, tonight I found I had one of these in my tying table drawer. I cannot recall ever really trying to use it. I put a #10 Parachute Adam's on it to see how it works. I had not seen the MRO video and didn't follow Brian Flechsig's instructions on orienting the fly vertically to the threader's slot but it worked anyway.
IT IS STUPID SIMPLE.
Funny, I think my wife gave it to me many years ago, and now I may never actually need to use it.
I read some Amazon reviews on this one. There are a bunch of listings for essentially the same tool, and none of them have very many reviews. I always start with the one

reviews. Some reviewers describe it as appearing to be 3D printed, and the finish being rough, along with other flaws; no magnet, threading hole not aligned with line slot, or completely missing, and delivery delays.
But if it actually can securely hold the fly in position aligned with a slot to thread tippet through while twisting the line into multiple wraps to tie the knot like I saw in the video
@kmudgn posted, that could be useful. But then hemostats make it a lot easier to tie some of the basic knots we use.
Beware....