What is wrong with this video and with their book on 한자 (漢字)?

ANSWER: They don't talk about Chinese sentences.

I have found that the best way to learn and "remember" Chinese characters is by reading them in sentences instead of in word lists. In other words, first you learn the Chinese characters and then you remember them by reading and writing them in sentences. For example, consider these Chinese characters:

人 (인) person

口 (구) mouth, opening

立 (립) stand, stand up, establish, immediately

門 (문) door, gate

在 (재) exist, at, in

有 (유) There is/are, to have

After you learn to read and write the above six characters, you remember them by reading and writing them in sentences. For example, here is a sentence that will help you remember the six characters above.

有人立在門口 (유인립재문구)

There is (有) a man (人) standing (立) at (在) the door (門) entrance (口).

If you can read and understand individual Chinese characters in memorable sentences and phrases, then you should also be able to remember them when they are paired together in less memorable words, which often come from Chinese phrases.

I like the video below, but it seems like they are more interested in teaching Korean words than in teaching Chinese characters. If you learn the individual characters in sentences and phrases first, the 2-, 3-, and 4-character words will come easier later.