In all tier 1 cities, which are at least 10, you can get 100Mbps broadband with about 750GB to 1TB data for close to 20 dollars a month. In villages (at least 100 thousands of them) and small towns (roughly 8 thousand of them) where most population resides, the story is different. Only wired broadband provider for them is govt. owned named BSNL whose service is quite unreliable. 4G high speed wireless is accessible everywhere for cheap though.

You're right in that "most" Indians probably do not have broadband access / 4G access. But the urban centers certainly do,and they have enough by way of people to become a huge market. To put it in context, there are at least 46 cities with population > 1M (2011 census), and the top 7 cities by population will certainly have access to broadband as well as cheap 4G. These 7 will account for 50M - 55M in population. In comparison, the US has 10 cities with > 1M population ( as far as I can see on Wikipedia). So even when you account for the lesser internet penetration in India as a whole, the number of people who can possibly access streaming services is quite large.