Sure it’s subjective, and yet he didn’t give any convincing reason, aside from clickbait, that this was a good metric.
But it’s not even a good video about complex Kanji because that is simply two random Kanji that are never even used in real life and just created by some random person. Something like 薔薇 or 鬱陶しい would’ve made a much more interesting video as these are actual, usable Kanji. Aside from that, he blathers on for 7 minutes but gives no real insight. So by pretty much any metric this is a video of a topic that is beaten to death, which provides no actual content.
If the video was, “Look at that, that’s crazy!” he could’ve said that in 30 seconds. But you can’t monetize a 30 second video.
His post seems to have been removed from /r/learnjapanese but there’s a reason it was at a score of 0. By any measure this is a poorly put-together, click-bait-y dead-horse-beating contentless video.