YouTube is bringing its skippable video ads to mobile phones and tablets, hoping to build on the success the company says the ads have found with PCs.

Viewers using desktop and laptop computers can skip YouTube's video ads, dubbed "TrueView," after five seconds. Advertisers only pay if a viewer watches it for 30 seconds or completion, whichever comes first. The operating theory for YouTube is that advertisers will pay more to reach a viewer who has chosen to watch an ad.

Skippable ads are obviously popular among consumers, but publishers that don't have the massive video inventory of YouTube have hesitated to introduce similar formats for fear of squashing large chunks of their video ad revenue in the short-term.

YouTube says that 65% of pre-roll ads on YouTube now allow viewers to skip them. That penetration coupled with the explosion of content consumption on mobile devices made the ads' extension a no-brainer, the company said.

Advertisers, meanwhile, are getting better at making the most of mobile, according to Jason Spero, head of global mobile sales and strategy at Google. Where most advertisers previously used mobile ads to extend their desktop campaigns, they are increasingly using different calls to action even when the creative remains the same, he explained. "Finally, we're starting to see people think of it as a complementary set of channels," he said.

Mr. Spero declined to say how much mobile revenue YouTube has brought in but cited an earnings call last fall during which Google CEO Larry Page said Google was on pace to generate more than $2.5 billion of mobile revenue across its different businesses.

Update: As All Things D notes, the skippable ads will initially only show up on Android mobile devices. That's because the pre-installed, Apple-built, YouTube app for iOS devices like the iPhone doesn't include ads. Apple recently announced that the YouTube app is not going to be pre-installed on future iOS devices, meaning that Google will begin offering its own YouTube app -- which will almost definitely include ads. "We're rolling out TrueView to Android this week, and then to all mobile devices," A Google spokeswoman said. "We can't comment on timing for other platforms."