The age of the Internet has meant an explosion of both new media to consume and new ways to consume it. There are more avenues for getting quality content delivered directly to you than ever before. It can be just as overwhelming to pick which service to use for streaming, downloading, or buying digital content as it is choosing which movie to actually watch!
Unfortunately, with the advent of all this new technology, there are of course some limits that have been enforced and placed in the way of consumers looking to enjoy content from a number of different countries and global regions.
To break it down quickly...
There are different contracts between distribution companies (like Netflix, Amazon Prime, Hulu, and other streaming services around the globe) and the companies that hold the rights to movies the public would be interested in seeing. For example, when the American Netflix DNS buys the rights to stream a movie in America, another company in a different part of the world may hold the rights to distributing or streaming that same movie for their region.