There is some truth in it, in every Pakistani is an Indian, but in every Indian is a Pakistani.
Pakistan and India were one country once. The inhabitants of both countries still are the same people they were under a united country back then, only with different nationalities now and though the cultures are different, there are also still many similarities.
I don't think it's mainly the movies though, it's also the fact that for so many years, it was one country, so the relationship goes further than just because people like movies and poetry. One of the other reasons is family, some of our Pakistani friends still have family members in parts of India and with some of them, they have regular contact.
When I see people from India, I also see Pakistanis in them and vice versa.