You have probably finished a course feeling confident, then blanked on the material a week later. That is not your memory failing, it is how you studied.
Passive watching feels like learning but barely sticks. Real retention comes from recalling the information, not re-reading it. That is why the most effective method is active recall.
After each lesson, close the tab and write down what you remember without looking. Test yourself on the key ideas before moving on. It is harder, and that discomfort is exactly why it works.
Space your review out too. Revisit the material the next day, then three days later. Two short recall sessions are worth more than an hour of rewatching the same video. Learn less, review more, remember longer.