Pretty sure that's a guy known as "Arclight" (it's even signed arclight on the side of the gun at 49 seconds).
Looks to be an M4 based rifle (likely a G&P judging from what I can tell from the receiver markings). Typical Generic red dot. you can get a similar looking rear stock if you get a "MOD stock", likely there's a "nunchuck battery" inside (it looks like this is the specific rear stock he used
). Front handguard is a Magpul PTS MOE, I suspect the vert grip is also from the Magpul PTS line.
Hope this helps.
The M4 is very versatile and you've made a pretty good choice, I myself own an M4 but I am kind of getting into the idea of picking up an AK for a custom project.
Any questions you have feel free to ask (but search first). You've really made a good impression, keep it up and you'll have loads of fun and when 18 be welcomed with open arms to the community.