Walmart added the ability to rent or buy movies and TV episodes to its website today, integrating the Vudu streaming service it acquired 18 months ago.

In addition to buying physical discs on Walmart.com, users can now stream or download from a library of roughly 20,000 titles Vudu makes available. Digital-delivery options will allow for viewing video directly on the site or to the other connected devices where Vudu has already established a footprint.

“Now this service has another outlet and it’s a vibrant, movie-buying population increasingly important to us,” said Edward Lichty, GM of Vudu.

That capability positions Walmart.com, which gets upward of 5 million visits per day, as a force to be reckoned with in this nascent marketplace alongside the likes of Apple’s iTunes or Microsoft’s XBox Live.

Incorporating Vudu into Walmart.com has always seemed the goal of the acquisition of Vudu, which was known mainly as a standalone set-top box when the startup was snapped up in February 2010. Since then, Vudu has operated somewhat at arm’s length though Walmart has plugged the service in store in various ways including the sale of cards facilitating digital video transactions.

Steve Nave, president of Walmart.com, saw no reason to get rid of the Vudu brand name given the reputation the service has built as a distinct identity. “Vudu is already a well-established brand in this space and we didn’t feel a need to mess with it,” he said.

The integration of Vudu represents a comeback for Walmart, which may sell more physical discs than any retailer but has suffered false starts in its digital distribution efforts. In 2007, Walmart shuttered a download service done in tandem with partner Hewlett-Packard, citing underwhelming demand.