When Vevo launched last December, the music video-centric joint venture—backed by competing record companies Sony Music Entertainment and Universal Music Group, investor Abu Dhabi Media, and even Google’s YouTube—had all the makings of what Lady Gaga would call a “Bad Romance.” But it’s actually been sweeter than Justin Bieber’s smile.

In five months, the property—Vevo.com and channels on YouTube, AOL and various CBS sites—has surged, hitting 44 million unique users in April, according to comScore. That’s a larger audience than Hulu, which Vevo also beats on some time-spent metrics, such as average minutes per video.

Such rapid growth has hardly escaped the attention of advertisers. Since launching with a dozen sponsors, Vevo has now run campaigns for nearly 100 brands, including blue chips such as Ford, Heineken, McDonald’s, MasterCard, Kmart and Elizabeth Arden. It’s quickly become a staple for movie advertisers like Lionsgate and Warner Bros. Buyers noted that while Vevo’s not pulling the same ad rates that Hulu does just yet, it’s already commanding CPMs in the neighborhood of $25.

Vevo’s traffic appears to have been driven largely by users searching for specific artists’ music videos (89 percent of its audience comes from YouTube), but the site is doubling down on original content. Having already launched half a dozen original series, including a short-form program spotlighting hot DJs, at least 15 more programs are in development for the 2010-2011 time frame. David Kohl, Vevo’s evp, sales & customer operations, said that several broadcasters already have expressed interest in licensing Vevo’s shows.

On the ad front, Kohl credited Hulu for raising the buying community’s expectations about online video: “[When we launched], the market was open.”

Buyers drew another parallel to Hulu. Like that property, they praised Vevo’s strong engagement numbers, its quality content and user experience, and its restrained ad approach. “They have this really robust, high-profile, high-quality content. What advertiser doesn’t like that?” asked Steve Minichini, president, interactive marketing, TargetCast. “And they have really smart ad integration. It’s not repetitive or annoying to users. I’d even call it polite.”

Vevo also has scored an unexpected success in the Hispanic world. According to Kohl, a considerable number of users select “Spanish” as the preferred language when logging onto Vevo; as a result, it reached 6 million Hispanic users in April, per comScore. “That was an absolute eye opener for us,” said Kohl, adding that about 10 brands have come on board specifically to target Hispanics, including Toyota, Warner Bros. and Colgate.

Vevo’s Hispanic skew is welcome, given how underserved the market is online, said Marla Skiko, svp, director of digital innovation, SMG Multicultural. “We are always on a quest for more relevant content for this audience because there’s been this big [empty] space. [Vevo is] definitely on our radar.”