Amazon’s on-demand streaming video offering just got a whole lot more attractive. The company announced today that they signed a deal with Viacom, allowing them to offer thousands of new videos from sources like MTV, Comedy Central, VH1, BET and Nickelodeon, among others.

In total, Amazon Prime will have over 15,000 videos available for streaming, including some very popular television shows. Amazon launched its video streaming service about a year ago with 5,000 videos. With today’s announcement, that number is now tripled.

The move comes just as Netflix struggles to rebound from a rough 2011. One of the ways it’s hoping to do so is by launching original, Web-only TV content like the new series “Lilyhammer.” That strategy is only in its infancy so it remains to be seen how it will play out. In the meantime, Amazon Prime is slowly emerging as a serious potential competitor to Netflix.

Wired’s Tim Carmody argued recently that Amazon is particularly well-positioned to emerge as a such a competitor, not only to Netflix but to cable television as well.

Amazon Prime still has some growing to do, and for now the service is tied to Amazon’s free shipping service of the same name. GigaOm’s Ryan Lawler argues that unbundling the two and launching a stand-alone streaming service could make the service an even stronger contender for Netflix’s throne as king of this space.

It’s worth keeping in mind that Amazon Prime Instant Video only launched in February of last year. Netflix has been around since 1997 and launched its Watch Instantly streaming feature in 2007. Amazon is rising fast, and its clear that digital content is a growing priority for the company, especially now that its also sells its own media tablet.