I’m racing since the 1990s. 3x, 2x, 1x. While clutch mechs and narrow/wide have improved drivetrain reliability a lot, in very muddy conditions you’re simply lost. I ride 1x ever since Eagle came out, dropped my chain so often when it got really muddy in races.
However, what is a little bit odd in the video, the drivetrain does not look so bad. And that he drops the chain so often. Of course, it’s hard to judge from a distance but based on my experience things usually look worse.