In just 30 seconds, the video sprints from one unlikely scenario to another: a pot-bellied partier cradles a Chihuahua; a bride flees police on a golf cart; a farmer luxuriates in a pool full of eggs.

Amazon’s new AI-powered video generator aims to broaden access to an upper-funnel channel that can be prohibitively costly to small- and mid-sized marketers. The videos themselves are fairly ...