Is this specific to this project or are you asking in general how to build youtube?
Building something like youtube would require fullstack knowledge. If you finish the first 6 FCC certificates, that would give you a lot of the base knowledge you would need to understand an app like that.
A professional developer would begin by developing a requirements definition that defines what needs to be done using non-technical language. In other words, describe what the software does from the point of view of the potential user. Then write technical specifications for how to do that. Then analyze the details of how. Then attempt to figure out how. When you need help, ask for help with specific details.