Hi,
I'm pretty sure there are ready solutions, I can't recommend any tho, as we usually build such software from scratch. Estimate for building it from scratch really depends on what you actually wish to be implemented from the features. Like if you wish cheap and quick solution, then some pre-made template for the FE can be used, and backend can have only basic functionality, and some rough estimate would be maybe a month. However it can easily be expanded to several months if you wish to upload videos from admin, cut trailers from the admin, have some more advanced streaming, CDN, basically if you wish more advanced CMS then it will take more time
If you have something in mind feel free to reach to us, we can schedule a call, go over the features, and I can send you more precise estimate tho.