Developing a site like netflix is a vastly more complicated endeavor than writing a channel for the Roku. While some devs here likely have experience with that, it is by no means a prerequisite for doing the work required to make a channel. I suggest contacting a reputable development company (possibly from the list of developers for hire) with your needs, and getting a quote. It will NOT be cheap. Do your homework on whoever you choose, you probably want some prior experience with the type of work you are requesting.