Back in February, T-Mobile U.K. scored a massive TV and online marketing coup with an innovative "flash mob" sprung on unsuspecting commuters at London's Liverpool Street station. The resulting videos and Life's For Sharing YouTube channel have generated well over 13 million views and thousands of comments. Now T-Mobile is back with more "community-building" through a mass-karaoke session held at another London landmark, Trafalgar Square. But this time around, the brand corralled YouTubers to turn up and join in with a video promo posted a few days before. Another demonstration of T-Mobile embracing its customers or one publicity stunt too far? You decide.

Title: T-Mobile's Hey Jude in Trafalgar Square

Stats: Posted just two days ago, the Trafalgar Square singalong (this video features a rendition of “Hey Jude,” but T-Mobile promises/threatens to serve up new songs in the weeks to come) has already been viewed 137,282 times and generated 515 comments. Even the high-definition version has been viewed 41,000 times!

What you see: The video opens with shots of the 13,500-strong crowd practicing with some of the 2,000 radio microphones handed out by T-Mobile's ad agency (allowing the video producers to pinpoint singers in the crowd). It's quickly obvious that this is no repeat of the previous flash-mob dance. The crowd starts singing along to “Hey Jude” (smiles and feel-good feelings abound), and then one really good singing voice is highlighted. It's Pink making a guest appearance with adoring fans.

Take Out/TakeAway: What began with the first ad as a smart piece of live event spectacle now feels completely contrived and overproduced. It's clear that T-Mobile realized it had an opportunity to build upon the massive success of the Liverpool Street ad that gave T-Mobile an image makeover—turning a boring business-customer brand into one perceived as cool by the kids. Whether the youth generation will connect with “Hey Jude” remains to be seen.