As he says, and my bad I didn't mention filtering air to your lungs as well. Most of my experience is in glass beading booths which self contain the blasting media. Like he says with media, it pulverizes on use and reuse not as good a result. Glass though fractures in smaller sharp edges, it can be used longer. Past a point though ALL media breaks down to be dust. The more trash you remove off parts the more you pollute your media as well and result drops off. Best to grossly clean part to remove easy-to-come-off stuff then blast to get off hard stuff.
That gun will work (I've had like 3 of them) but expect high wear at the actual nozzle inside, they wear pretty fast. And you need lots of air VOLUME at the 100 psi he says. That usually means a pretty good size compressor. You can easily drop the bag to just extend a big plastic hose into a free standing bucket. I mod separately to rig a small pressure line with valve to the bucket itself, the outlet ends right at the inlet for the hose. The media sometimes crams up solid around inlet and clogs, a slight amount of air disturbing things there can stir up the media enough to keep it flowing well. The moisture thing he mentions...... .............
PROTECT THOSE EYES AND NOSE, this stuff works like gangbusters if worked out right, you will have it EVERYWHERE. I used to blast in a big room at a heat exchanger shop, blasting 30 foot long exchanger outside shells. You worn an entire suit with piped air to it. The blast media was like welding slag broken up into very small bits, it left a gritty pattern that they loved on the shells. Instantly removed even the hardest glassy flux remains from welding. Would eat to the bone if you shot your hand for five-ten seconds. The gun had like 1 inch outlet and you held it like a cannon. It had a lot of force kicking back.
I'm building my own glass beading cabinet, about 80% finished now, a cheap $110 Chinese kit but with some custom mods to bring up the efficiency to match the expensive $2K-$4K models. Big enough to get car heads in it.