This is a bunch of nothing. I'm watching his shuffles over and over again at the timestamps indicated, and they're not suspect. Heck, at the Pro Tour, Ari Lax was accused of stacking the deck as well. When playing against an Ascendency combo player, his opponent cracked a fetch and, on multiple occasions, found multiple Ascendencies at the bottom of the deck. He actually called a judge over during sideboards to make it look like a rules question, and a judge observed the rest of the match. It actually happened again in game two, even with the judges watching. Sometimes, lands end up on top. Or on bottom. There is variance, after all. (Ari told this story on a recent episode of Cedric Phillips' podcast).
With most shuffling techniques, it's actually super easy for someone to naturally keep the same card on top repeatedly, especially when you don't riffle shuffle (and Magic courtesy is to not riffle your opponent's deck, generally speaking). This is due to the fact that you are naturally gripping the top of the deck with your palm, and the top card has the best grip and won't naturally dislodge. This is why you should alternate mash shuffles with cuts. I actually have a tendency to deliberately cut away the top card because it "feels" wrong for me to leave the top of the deck seemingly unrandomized.
I noticed this was happening myself when I first started playing paper magic. Now I have this weird pattern where I grab the bottom half of the deck, put the top half of that on top, and the rest on the bottom, then mash a few more times, then grab the bottom half again, put the bottom half of that on top and the rest on bottom, then mash a few more times. My goal is to ensure that by the end of it, I have no idea where the top or the bottom of the deck ended up (and they're certainly not where they started). But I'm quite deliberate about it. Before I started doing that, I found that the top of the deck basically never moved, and that bothered me.