When RiffTrax first launched in 2006, this was the only type of product we offered! We used MP3s (similar to what folks knew back then mainly for podcasts and burning a "mixtape" CD) to allow us to create MST3K-style commentaries for big blockbuster movies that we could never get the rights to do as VOD.
Back then the easiest way to get a copy of the movie was through a Blockbuster rental, or Netflix was sending only DVDs! But now you can find most of the same movies we used for our commentaries on the streaming services - see each product page for a helpful block of links to such services, where applicable.
And check out the RiffTrax app to easily sync our Jokes to your Movie!