Couple things about the video.
...One, wear safey glasses (even outside), brass swarf (shavings) are hell on your eye's.
...Two, this trimmer is similar to the WFT and the Giraud secept the Giraud is solid mounted and integrially driven. The WFT drives with a handrill just like this one but uses a zero tolerance (runout) roller bearing insert that accepts sub inserts (steel) that are chamber cut to match the caliber family so the insert rotates with the brass (no marks on the case).
I would exchhange the import 2 flute end mill (that does the cutting) to a solid micrograin tungsetn 4 flute fast helix end mill for a couple reasons. One the 4 flute will cut sommoth at a lower speed, it will last forever and contraty to the video, a HSS mill will leave a tiny burr inside the case mouth and on the id because the brass is much softer than the cutter material so it 'flows' a bit no matter how sharp the cutter is and a 4 flute eliminates all chatter.
Also, contrary to the video, it's advisable to chamfer the id of the case mouth prior to inserting any pill, you want a smooth umimpeded entry and a square shoulder will not give you that. On boattails, I strongly suggest a VLD chamfer for ease of insertion plus a VLD chamfer won't scar the pill as it enters the case mouth.
All 3 are basically the same principla, CTS. WFT and Giraud.
Because the end mill is the driven shank of the tool, I don't like to use a handrill. I prefer chucking the tool in a collet in one of my lathes and using both hands to guide and cut the necks. Just my preference.