A cigar cutter is a device for cutting the end of the cigar wrapper where it goes in your mouth, so you can draw the smoke through it. If you get a cigar guillotine that accepts a finger or thumb in a hole at either end, with a hole for the cigar (roll of 120) in the middle that the blade cuts through, that's what the fellow on YouTube uses. Mark the film 46 mm from one edge, chosen so you keep the 6x4.5 number track (which will become the 4x4 track with a little extra spacing on the 127 -- the 6x6 track barely lines up with the 4x6 ruby window, as I recall), bring the blade of the cutter into the film backing with gentle pressure, and start rotating the film roll as you slowly increase pressure. You'll be able to feel when you reach the core.
Once cut, you'll go into a darkroom or dark bag to respool the wide strip onto a 127 spool (and then backward to another 127, so its oriented correctly); while in the dark, you can unwind the 16 mm strip, separate it from the backing, and put it into an old black plastic or metal film can for later use loading a 110, Minolta/Kiev 16, Yashica 16, or possible one or two other varieties of 16 mm film cassette (of a sort that doesn't need perfs).
The Minolta 16 QT is arguably the best camera in that line -- it's got a larger frame (13x18) than the 16, 16 II, and MG (10x14). If the meter works, it can be operated on a 3V lithium coin battery with a conductive spacer; if not, you can set the exposure manually (with a little trickery, as I recall). It's got a good lens, and is the only one of the Minolta 16 family that can be focused (the MG had fixed focus with a slide-in close-up lens, but it was four feet, or hyperfocal). I like my Kiev 30 best -- it's the tiny form factor of the Minolta 16 II, but has a focusing lens and somewhat broader shutter speed range. No flash sync, though; you need a Kiev 303 for that (and give up some middle shutter speeds). None of these depend in any way on sprocket holes, so they work fine with unperforated film, or single-perf loaded with the perfs toward the cassette bridge (though the Kievs will run the image into the edge of the sprockets with single perf film).