• by Gavin O'Malley , Staff Writer @mp_gavin, October 4, 2011

Do you put mobile video -- including the tablet kind -- in a different bucket than PC-based video? Usage behavior differs, and the buying may be separate, but, considering the way the world is going, it's best to factor these channels into your formula.

With that in mind, we bring your attention to new eMarketer data that identifies video as increasingly responsible for a surge in mobile advertising.

Indeed, albeit from the smallest base, video is the fastest-growing mobile ad format, eMarketer reports, while estimating that mobile video ad spending -- at $57.6 million this year -- will grow at a compound annual rate of 69% between 2010 and 2015 to reach $395.6 million.

This year, messaging-based formats still take the largest piece of the pie, accounting for $442.6 million in spending, according to eMarketer.

But next year, it bets, banners and rich media will be even with search -- each getting 33% of spending, or $594.8 million. That will put them ahead of messaging, which will fall to just 28.2% of all mobile ad spending next year.

Moreover, by 2015, banners and rich media and search will dominate further, and messaging will have shrunk to 14.4% of the total -- though still growing in terms of dollars, according to eMarketer principal analyst Noah Elkin.

"Even with Android and Apple setting the pace, marketers will still need cross-platform advertising solutions to reach the bulk of smart device users," Elkin notes.

Overall, spending on mobile advertising will top $1 billion in the US for the first time this year, eMarketer predicts. The reason? The continued rise of smartphone adoption, long with rising mobile Web usage, which together have made the market more attractive to advertisers.

By the end of this year, 38% of US mobile users will have a smartphone and 41% will use the mobile internet at least once each month, eMarketer estimates.

All told, advertisers will spend nearly $1.23 billion on mobile advertising this year in the US -- up from $743 million last year, according to eMarketer.

By 2015, the US mobile advertising market is set to reach almost $4.4 billion. This includes spending on display ads -- such as banners, rich media and video -- search and messaging-based advertising, and covers ads viewed on both mobile phones and tablets.

EMarketer previously forecast in September 2010 that US mobile advertising spending would reach $1.1 billion in 2011 -- up from $743 million in 2010. The revision, according to Elkin, features significantly higher growth levels throughout the forecast period.