Some of it comes from big things. I forgot to reload once. In one stage I reloaded an extra time and that threw me off. I also had an FTF which hung me up on another. But there are plenty of small things. My reloads are pretty slow, and I'm not too efficient moving through the course. I'm also slow at getting on the sites at critical points. Some of those I can work right here in the living room if I just get off my bum.
I just watched the video. Your trigger speed can come up some, but it is not the biggest thing. Order of engagement, too many starts and stops, not looking mag into the gun, getting lost and wondering around a bit, standing reloads that don't have to be standing reloads. Some more matches will help.