I want to build up a website like Netflix

My first advice, consult with a digital media attorney immediately. If you do a little research online, but what you'll want to search for is buying licensing rights to stream content - Netflix isn't buying copyrights, they're just buying a licensing right to stream the content from the copyright holder.

Netflix is constantly negotiating these deals, and I'm sure the details are kept under very tight wraps, and away from their competition like Hulu and Amazon.

I think you should refocus your goal first, make building a streaming service a 10yr or 15yr plan, why? To get content people want to watch, it won't come cheap. I'm sure that Netflix, Hulu, Amazon, etc are paying 10's of millions of dollars a year for a single license to stream a single TV series, for a single year, every year. Movies I'd guess are a couple million dollars a year, every year, for the license agreement.

I don't know how old you are, or if you remember, but Netflix started their humble beginnings by mailing DVD's to it's clients, you watched the movie, mailed it back when you were done with it, and they'd mail you the next DVD. That's a much less expensive way to rent movies - it's like the old school movies stores that rented physical media, but did it via online and the mail. That was an ingenious move at the time. And as Netflix made more and more money, they were able to start their streaming service.

Amazon of course already has tremendous capital from it's retail sales to have started it's service, and Hulu is owned by some very large companies, including Disney, 21st Century Fox, and NBC Universal to name a few (there's more!).

So unless you're worth probably over 100-200 million right now, I think it's going to be difficult to get streaming rights, and be profitable.

Maybe first thing about ways you can grow into that space - the great thing about the web is, you can make the couple hundred million dollars you need, in something else first. The brothers who started Stripe, are both worth over 1 billion dollars each at 26 and 28 years old I think.

Maybe you start off as a movie/tv review site, and with maybe discussion forums, and that grows into you starting to dig up deals, coupons, discounts for movies and movie theater snacks. Find a way to start much more simpler, and grow into that space you want to be in with a long term plan.

As far as languages to write this in, it doesn't really matter, what you're most comfortable with, they are all capable of doing so.

Thanks u really for this answer and I really appreciate it. It looks impossible for me to do sth like this one. And actually by having Netflix so no one would be to trust my service in short time but also in a long time of adding new movies and so on but money matters. ;)