Research firm eMarketer reports that more than 45 million Americans watched video on mobile devices this year, up from 29 million a year ago.

Smartphones dominate as device of choice at 90 percent.

Looking ahead, eMarketer forecasts the number of mobile video viewers will increase to 54.6 million in 2012, 63 million in 2013 and 69.3 million in 2014, 78.1 million in 2015.

Whilte smartphones are the device of choice at 90 percent currently and increasing to 98.5 percent by 2015, tablets such as the iPad are helping drive up video viewing, eMarketer said.

“As tablets attract a larger share of video viewing, smartphones are benefiting because most tablet users also own smartphones and typically have the same apps on both devices,” said Paul Verna, an eMarketer senior analyst. “With more video content flowing to these apps, users are choosing their preferred screen at any given time. Often this means toggling between tablets and smartphones, or between laptops and any number of entertainment devices.”

For the study’s findings about overall online video viewing, read here.

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