Last.fm and Universal Music Group have announced today a partnership that will allow Last.fm users to view "thousands of full-length music videos" from UMG's catalog. The videos—which will include those from popular artists like Jay-Z, The Killers, Amy Winehouse, and Kanye West—will be available on-demand and for free, and UMG says that artists will get a payout every time a video is streamed.

The two companies claim that the partnership provides a "massive boost" to Last.fm's music video collection and that Last.fm will be able to provide recommendations to users watching certain videos based on their musical tastes (also known as "scrobbling"). Like other videos on Last.fm, users can leave comments on each video and watch them in fullscreen mode, but they won't be able to embed them on their personal blogs like they can with YouTube videos.

Although UMG and Last.fm say that the streaming videos will be ad-supported, they aren't being treated in the same way as Last.fm's streaming music. The videos don't have any ads before, during, or after them (which is quite nice), and it appears as if you can watch them as many times as you want without being prompted to pay for anything. The companies say that the share of revenue that artists get will come from ads shown next to the video content, but for now, it doesn't appear as if those ads actually exist yet.

Still, it's clear that Last.fm is quite proud of the deal, as it plans to showcase UMG's videos exclusively on the site for the first month. "This is a hugely empowering partnership that really takes Last.fm to the next level," Last.fm cofounder Martin Stiksel said in a statement. "We want to offer a video library that rivals our unparalleled music catalogue, as we work towards Last.fm becoming the only place you need to go to for all music-related content, and this deal marks the first step towards that goal."

Indeed, it is only the first step, as there are a handful of other sites where users can watch music videos. YouTube is still the de facto standard for most of the Internet-using public looking to watch music videos for free, and YouTube has even stated that it wants to eventually host "every music video ever created." MySpace Music is also hopping on the bandwagon, not only with music downloads but also with streaming videos from the plethora of artists that showcase their music on the site. And, of course, there's always Yahoo Music's video selection, as well as MSN Music's videos. If the mediocre quality of videos on other sites aren't enough, users can head on over to PluggedIn, launched this April, that offers high-definition videos directly from Universal, EMI, Sony BMG, and a handful of videos from Warner Music.

So what, exactly, is the benefit of watching music videos on Last.fm instead? For one, it makes Last.fm a more complete destination for users' general music needs, as it now offers both music and video streaming for free (in addition to Last.fm's famed scrobbling feature, of course). If you're already a Last.fm fan, there's no longer a reason to go to yet another site in order to watch the latest Kanye video—you can watch it right there! However, attracting users of other sites (ones that aren't Last.fm users already) may prove to be a challenge because of the level of competition elsewhere on the 'Net.