YouTube is a big success on cable boxes in Hungary. So when will it launch elsewhere?

TV viewers love YouTube, especially if it’s on their cable box: That’s the gist of new numbers coming out Hungary, where the video service is now streaming more than a million viewing minutes per day to cable boxes, according to UPC Hungary.

The cable TV operator, which is part of [company]Liberty Global[/company], launched YouTube and a number of other apps on its set-top boxes three months ago. Since then, more than 50 percent of [company]UPC[/company]’s susbcribers with access to the app have tried it, and half of those have come back for more and become repeat users. Equally impressive: The average YouTube viewing session on a UPC set-top box is 45 minutes long.

Of course, those numbers may also make some people in the pay TV world nervous. If people start to watch YouTube for close to an hour a day, do they possibly watch less traditional TV, leading them to eventually ditch cable altogether? UPC’s numbers suggest that’s not the case, or at least not yet.

Most YouTube viewing on cable boxes happens during the day and outside of the traditional prime time window, according to UPC Central and Eastern Europe CTO Arpi Jordan, who put it this way in a blog post:

The service is building value for our customers, our content partners and ourselves, and (…) online video and pay-TV channels can co-exist as parts of our service bundle.

That’s a point others have been making for some time; [company]Netflix[/company] is continuing to strike partnerships with pay TV operators in Europe to bring its app onto set-top boxes, and [company]Comcast[/company] is looking test its own online video service on its Xfinity boxes later this year. However, so far, many of these tests and partnerships have been limited to certain devices, and overall small subscriber numbers.

The difference with UPC’s YouTube partnership in Hungary is that it is using cloud virtualization technology from [company]ActiveVideo[/company], which means that YouTube’s app is rendered in the cloud, and then sent as a video stream to legacy set-top boxes — an approach that could potentially be brought to millions of subscribers in the U.S. as well.

So far, YouTube, Netflix and others have kept quiet about their plans for similar partnerships with U.S. cable operators — but numbers like the ones coming out of Hungary might help to change that.