Unfortunately, I have had too many occasions to practice my hole plugging technique. A few things I noticed about that video.
First, I bet those side cutters (dikes) don't work so well after using them as pliers on the screw. He showed a pair of needle-nose but then attempted to use them wrong; end on rather than from the side. Also not sure why he felt compelled to unscrew the screw rather than yanking it out. The next step is to use the rasp on the hole anyway...
I have never gooped up the hole rasp with cement, just stick it in dry. Works fine.
The instructions generally tell you to liberally cover the plug in cement. This is for the tire, not the plug. Yes they will work dry if you don't have any cement, like when you discover it dried up in the unopened tube. :angry:
I would finish deflating the tire before plugging for reasons noted above.
I would definitely NOT cut off the tails on the installed plug until you know there is no leaking. Check by inflating tire and spray with soapy water if available, or listen very closely if it's quiet enough. It is much easier to yank the plug out, or try to weasel in a second plug (for bigger holes) if the tails are still there.
Nice that he has a source of compressed air handy...
Gloves for a roadside repair are a great idea, IMO. No, this ain't brain surgery, but that sticky string gooey stuff getting on your fingers with no way to clean up afterwards means your gonna get that crap all over the rest of your fancy riding gear.