Well as someone who has punched paper with a GLock and run one in competition I'll go ahead and say whats on the video is pretty solid.
The sights suck and NEED to be replaced, they are just the worst sight picture and fragile too, I can remember seeing them wiped off the gun while clearing malfunctions, one guy used to keep a baggie of spares because it happened so frequently (and at the time there wasn't many aftermarket replacements available). I've used Novaks on a GLock and they were very good, Heinies are probably a bit better. Bomars rock when low mounted and buried in the slide but thats a high dollar option. No matter what the factories must go for competition.
The trigger should be modified as much as allowable, depending on the sport and division, in IPSC you need to get as close to 5lbs as possible with factory parts if shooting in Production, any other division go as light as you can.
The factory mag button is a bit small but the one off the 17L is a bit too long, I had issues with it and trimmed it down, eventually I had a custom Aluminum mag button made and it was a bit longer than factory but quite a bit shorter than a 17L, I haven't tried a Gen 4 but you might be able to get away without modding it.
Magwell? Depends on division, the frame slug is useless for IPSC, its not allowed in Production and in Standard or Open you'd want a magwell.
Slide grooves? Had 'em, if you get a proper high grip on a GLock you will too. The great thing about the glock is the low slide/barrel, but it comes at a cost. The add on beavertail in the video wouldn't be allowed in Production but would be tempting to run on a Standard division gun.
I'm not sponsored by anyone so these thoughts are my own from experience[/QUw
ever hear of paragraphs, lol.