After programming in c++ for a while i picked up java knowledge very fast and easy.
Programming in one language is similar to another it's like learning a new language that is closely tied to the one you know like French and Spanish.
id say start with c++, after you learn it the other languages are cake.
Not a good idea C++ is more complicated than Python or Java. You've only scraped the surface of C++. It's easier to learn the, "common data structures, logic, loops, recursion, other design patterns and Advanced OOP concepts then language itself becomes irrelevant--just a matter of applying syntax. " To learn these concepts you can just work through a low level language but end up learning everything about programming and then later apply to to higher level languages.
i didnt use any books to learn, im 16 and if you take your time you can do it.
Books are written by experts and not students. They are also more cohesive and teach you how to design programs. Your video's are nice but they don't teach you much. Your better off mostly ignoring videos if you serious about learning all there is to know about the language and programming. Videos only provide a brief intro to the language.