What is the ruling on downloading clips from a website that prohibits it, and is their prohibition considered valid, and what about benefiting from what was downloaded previously?

As long as the website prohibits downloading clips from it without permission, it is not permissible to bypass that. One benefits from it within the limits of what is permitted, such as viewing or listening to clips without downloading them. Some scholars are of the view that if something is for personal benefit and not for earning money, then there is no harm in copying and downloading it.