As a strong tournament player, I have to say that no matter how strong you are, you are always going to make horrendous blunders, especially under time pressure. Each games may have 40 or 50 moves. To play each move without making one mistake is almost impossible. There is always going to be a flaw, whether it's one move deep (hanging your queen, or five moves deep).
Sometimes the mistake is a very minor positional one that can cost the game in the long run.
Keep in mind, these players are playing at a level that is completely mind boggling. They have memorized the first several moves and know all the major variations. They have incredible visualisation skills and can see variations of moves, ten, twenty moves deep. They basically have a mental chessboard in their head, and can even play blindfolded. Most of the top GMs can play several blindfold games at a time.
I have been playing for many years and am probably rated around 1700 or 1800. A 200 point difference means that the higher rated player will win 75% of the games against the weaker.
1800 is considered a very strong player. Probably only around 10% of all US Chess Federation members are at this level or higher.
200 points above that is the expert level (2000)
200 points above that is the master level (less than 1% of all players) (2200)
200 points above that around where most International Masters are (stronger than regular masters) (2400)
200 points above that is where most Grandmasters are (only a few hundred players at that level) (2600)
200 points above that is where the super elite GMs and world champions are (Fischer, Kasparov, Carlson, Anand) (2800)
Anish Giri looks very good looking and sharp in that video. I've seen players at his level look like homeless guys.
This blunder is nothing compared to what some may consider the worst move by a super GM. Kramnik (a world champion) was playing a computer and missed mate in one!!
A person who plays casually for a few years, and beats all of his buddies, and is considered a pretty good player would probably be rated around 1200.
This kind of stuff just doesn't happen at that level in a standard time control game (not a blitz or fast game). It's kind of like Michael Jordan missing 100 free throws in a row.