Because I haven't heard about it before this comment? I am taking a look now, it looks interesting.

I usually like to download the whole files anyway and keep them on my external big drive to make sure I have them when a movie stops being popular and becomes harder to find on torrents.

Also, I have an external projector that can play movies from a USB and having the full file available for me to copy onto the USB in few minutes is very useful for my use case.