Well, it's not easy because distribution rights are so scattered. GOG said that they had at least one studio they spoke with was open to the idea (my guess is that it was Lionsgate), and other studios had said that they would follow, but they didn't want to be the first to do it. And even if GOG were to be able to do it, sales of the films would have to be regionally restricted. GOG put the idea up for a survey or something and the majority of users shot down the idea. =\
If you want to start with getting in touch with a studio, I suggest Lionsgate, I think that they are most open to taking such chances.
Alternatively, there are plenty of European studios and distributors with large catalogs of films that could potentially be made available online, and some of them may not be in such a mess with distribution rights. If one is particularly savvy, there may even be business opportunities open for one's self in such circumstances.