It is possible to legally watch movies in Spanish on YouTube. Search for the movie you have in mind to see if it is available. You can also go to the "Spanish Movies" YouTube channel to browse a selection of Spanish language films and documentaries.
While many movies are available for free on YouTube, there is a rental fee for some newer films. Rental films are only available to watch for a short time period, and rental prices vary depending on the film. Viewers can also buy some Spanish language movies from YouTube for the price of a normal DVD.