Choose a movie-streaming service. To choose the best movie-streaming service, you have to consider the price and service offerings and your method of watching the movie. You can own a digital copy of the movie on a computer or a handheld device via an Internet download service such as CinemaNow, or you can watch "Spider-Man 3" streaming on an online rental service website, such as Netflix. When opting for a streaming service, you can choose to watch the movie on a computer or through a gaming device connected to the Internet.
Sign up for an account. Once you've selected the service you want to use to watch "Spider-Man 3," sign up for an account. You may need to provide a credit card number or PayPal account information at this time. If you think you'll watch more movies in the future online, opt for an unlimited online rental service, like Netflix. If you just want to download a copy of "Spider-Man 3" for keeps or you don't think you'll often rent movies online, opt for a service that lets you pay-as-you-go, like CinemaNow.
Search for "Spider-Man 3." Spot the "search" box on the main web page of the service for which you've registered. Type "Spider-Man 3" in this box. Alternatively, you can find an alphabetical listing of movie titles and look under "S." You can also find the movie under the categories "Action" or "Adventure."
Select the movie. If purchasing a copy, you need to add "Spider-Man 3" to your cart and proceed to the checkout before you get your download. If watching the movie streaming on an unlimited plan, you can select to begin the streaming at any time by clicking on the "Watch Now" button on the "Spider-Man 3" page.