Of course back in the days before YouTube and fast internet came along (where YouTube Towers is now was once a field
) sites that hosted video clips were often self contained - ie they hosted the clips themselves and often had their own proprietary players (like TV Ark does) to play them, typically some cobbled together Flash creation. And for any decent picture quality the files were huge compared to the typical internet speeds of the era.
Vimeo and YouTube rewrote the rules, coming in at pretty much the right time to take advantage in the mid 2000's as broadband began to become both cheaper and ultimately the norm, allowing any Tom, Dick and Harry to stick a video on their website without having to host it themselves.
TV Ark do say they have the blessing of various ITV companies and libraries to use their material, which may (or may not) be enough to placate the automated bots so far as copyright strikes go.