What languages does one need to know to build websites like Youtube?

I am working on a video website in a niche area – includes most of the youtube features as well as more. I have used the software bluevoda which allows one to build sites without knowing html or similar languages. However the site needs more customization, which isn’t possible trough a software. So I need to know exactly which languages are needed apart from html?

not that more much ya need!!!!