Ifin a shooter doesn't want to pay retail for ammo (which is way to high-not to mention the scarcity and scalper prices) and doesn't want to invest $$ for a press, dies, maybe a powder measure, and other reloading items, the Lee Loader is a good reliable alternative. I reloaded boxes and boxes of 12 gauge shotshells back in the late 60's/early 70's with one and never had a problem. While not as versatile and fast as a press, the Lee will fill the need for the occasional shooter. I've never heard of anyone having problems with one either loading shotshells or metallic's if proper procedure and care is used. Knew a guy who loaded alot of 38 Spec and .243 Winchester with the Lee and he had reliable and accurate ammo.
Downside with the Lee is it's slow and quantity is poor ifin you do alot of shooting, almost IMO as rolling yer own paper cartridges for cap and ball, which I don't do as I like using loose powder and the rammer. I would rather spend my time doing other things than sitting for hours making paper carts' which get shot up way faster than trying to be 'Old Timey". The powder measure Lee provides is set at a specific grain weight for certain powders so if ya want to load X grains of a certain powder that the Lee measure isn't designed for yer outa luck. You can buy the set of Lee's plastic dippers that will allow the reloader to use other powders and grains, they're pretty cheap, less than $20 last I knew (Covid crap may have increased them, if they can be found). I see Lee upped their double cavity molds from around $20 to $28, Ebay scalpers are selling them $50-75--horse thieves!!! As far as slow, I recall spending alot of time reloading 5-8 boxes of 12 gauge trap loads the night before shooting and shooting them up alot, alot faster than I reloaded them. Why I started using a shotshell press.
In regards to the video's author (Darto) of getting such a difference in fps between using his adjustable brass powder measure and in using his press, the heavier crimp he used with the Lee tool could make a big difference. I'm curious though when he advised he was using 35 grains of FFF black if he used the grain graduations that are marked on the side of those style/make of measure or he weighed out 35 of FFF and to see where to set the plunger.
Back in the 70's when I bought my TC 45 Hawken cap rifle, I bought one of those style of powder measures. I noticed that whatever setting I used on the numbered marks the manufacturer had used, that the measure always threw a higher grain weight of FFF black when checking the weights on a scale, around 3-4 grains. Same when trying out FF black. Sooo-using my RCBS scale I adjusted the powder measure plunger to various weights and marked the setting on one of the plungers smooth sides with a needle file. Did this with both FF and FFF black marking each grade on different sides, although I shoot FFF black through the TC most of the time.
In case Darto was using the manufacturers markings for 35 grains, he may have (may have) been loading more than 35 grains which could have accounted also for the increased fps/pressure. 35 grains of FFF in a 45 Colt case is pretty stiff, even 30 is, but if that funneled, adjustable measure throws more powder than the marks set by the manufacturer like mine did, those loads could have been 35+ of FFF. If his was off like mine and throwing higher than the marks indicate, 2-3, 4 grains could make a big difference. Darto may wade in on this post and say. Person could do like I do when loading black powder rounds and buy Lee's dipper kit which has 12-15 measures with various capacities. I load both 44 Colt and 45 Colt black powder rounds (use a RCBS press), but not my smokeless powder measure. From what others have posted in using the dippers I pretty much knew which ones to use, but checked them out on a scale using both FF and FFF. They're pretty consistent and accurate if a person uses the same method of dipping for each round. Just thought I'd toss this info about the brass adjustable measure in the fray. The Lee hand loaders are pretty accurate and reliable if used right, but slow and tedious to load with.