The Doritos Super Bowl ads are available on YouTube. There are other websites online that host them as well, such as Super Bowl Commercials and Superbowl-Ads.com.
Watching commercials online requires an Internet-accessible device, such as a computer, tablet or smartphone. Go to the YouTube website. Type "Doritos Super Bowl Commercial" in the search box. It may help to filter by the year of the Super Bowl itself.
To watch the commercials on one of the other sites, go to the home page and browse through the commercial offerings or use the available search tools to quickly navigate to Doritos commercials.