Walmart has a secret weapon against Amazon. Maybe too secret.

The Vudu Inc. application is displayed on an Apple Inc. iPhone in Washington, D.C., U.S., on Tuesday, March 27, 2018. Walmart Inc. has a vast arsenal at its disposal in its battle with Amazon.com Inc. -- stores, trucks, warehouses, even cloud-based data centers and a blockchain-enabled supply chain of fruits and vegetables. But there's one weapon it hasn't deployed: Vudu, the video-on-demand service it bought eight years ago. Photographer: Andrew Harrer/Bloomberg

Walmart Inc has a vast arsenal at its disposal in its battle with Amazon.com Inc: stores, trucks, warehouses, even a blockchain-enabled supply chain of fruits and vegetables. 

But there’s one weapon it’s barely deployed: Vudu, the video-on-demand service it bought eight years ago. Back then, Netflix was available only in the US and Canada, Amazon was still a year away from offering free videos for its Prime members and Apple had just released its first iPad. With a library of 5,000 films from all the big studios available at the press of a button, Vudu promised to “revolutionise” the home-movie experience when it debuted in 2007.