It is possible to find full versions of Hindi movies on YouTube. Simply search for the movie you have in mind to see if it is available on the website. You can also go to the "Indian Cinema" YouTube channel to browse a variety of Hindi movies.
While some movies are free to watch, there is a rental fee for other, usually newer, films. Rental films are only available to watch for a short period of time, and prices vary depending on the film. It is also possible to buy Hindi movies from YouTube for the price of a normal DVD.