Those squiggly or scribbling lines could be true. Maybe they are good at what they are doing. But why should you follow them? Technical analysis is a process to somewhat predict the future of the market. But it is never 100% accurate and never will be. You can guess it to an extent and that is how people trade. As long as you don't follow those videos or those people then you are good. But if you are foolish enough to trust those videos, then that's a "you"problem.
It doesn't matter if you are copying others strategies or not. What is most important is to make profits. Technical analysis can complicate things. If someone opens a higher timeframe for the bitcoin pair he will clearly see where the price can go next. Some YouTubers use that kind of analysis to show how knowledgeable they are so that they can attract more followers to their channel. Those complicated analyses have nothing to do with actual trading.