Learning is all about using your current knowledge and understanding to refine and augment those mental models.
Be aware that many people don't watch videos to learn, they watch to be entertained. They think that they are learning, but really they are just watching animations. In the end, they can't actually do any of the math. They haven't actually learned anything. In the same vein, that's why TED talks are so popular. It's like eating dessert... all sugar and no nutrients.
I'm not saying that 3b1b videos aren't instructional, but rather that they are so well put together that they can satisfy the entertainment-seekers while still offering meaningful content.
The question is, then, why don't you get anything out of the videos? That brings us back to the problem of mental models of understanding.
If someone teaches a subject from a completely different perspective, it may be that it confuses you as your brain tries to harmonize the two conflicting mental models, and the video moves along too quickly for you to be able to benefit from the realignment.
This is not an attack on you, btw. In fact, I believe that this realization helped me a lot as an educator to be patient when teaching. Furthermore, it does not mean that your initial understanding is wrong, but that it is a different perspective than that which is being presented by the instructor.
Alternatively, it may be that the videos move through a particular concept too quickly. I find this is an issue, too. Once I understand something new, I like to almost daydream about the concept, exploring it mentally so that I understand it from a lot of different angles. I think of it in different situations and to see if my intuitions make sense, and if they don't I ask for clarifications. You can't do that when watching a video because it doesn't stop to answer your questions.
I like 3b1b videos. Some of them I can binge on all day simply because they "click" and make sense. Others I have had to spend days (or weeks) thinking about in order to digest and understand the perspective that Grant is trying to convey. They are definitely high value and I greatly appreciate Grant's work, but I definitely have to work, too, in order to benefit from some of them.