Korean Dokdo propaganda videos are pretty much all the same. When it comes time to prove Korean claims, they just flash through a bunch of old Korean and Japanese maps and documents with little or no explanation, but with plenty of background music. The reason they do that is that they do not want people to look too closely at the evidence because then people might start asking such questions as, "Why do the old Japanese maps show Liancourt Rocks (Dokdo), but Korean maps do not?"
The Korean videos are designed to play on Korean emotions while relying on people's ignorance of the facts. That is why we see many Korean commenters here claim that Korea has a lot of evidence to support her claim on Dokdo, but then those same people are unable to explain what that evidence is.
Anyway, enjoy the video. At least, the music is nice.