YouTube is getting the most love from smartphone users across the world and banks should take note of the deepening affection.

Indeed, the video streaming resource accounts for 17% of mobile data bandwidth usage and 45% of total video streaming traffic, reports network firm Allot Communications in a study released this week. And that stat comes on top of an already major growth curve for the sector. In a nutshell, mobile data bandwidth usage is growing in popularity like a Jersey Shore cast member two years ago: usage shot up 73% during the second half of 2010, with video streaming driving the growth, finds the report. Video streaming accounts for 37% of mobile bandwidth.

For banks, this obvious growth trend definitely matters. With mobile banking taking the lead role in financial innovation news for months, knowing how consumers are actually using their smartphones is essential in helping to craft and develop strategies for the mobile channel. In other words: If Justin Bieber can find fame through YouTube, banks can find profits through the medium.

Equally important news found within the Allot report is the surge of consumers accessing social networks from their smartphones. Twitter’s and Facebook’s usage soared by 378% and 267% respectively. I’m no psychic, but I can’t see these relationships breaking up any time soon.

The data for the study, called Allot MobileTrends Report, was collected from July 1 to Dec. 31, 2010 from mobile operators worldwide.