Over the Top video viewing in the US has grown dramatically in just a year, both streamed and downloaded, on stationary as well as mobile platforms.

According to a new report from Knowledge Networks, smartphones, videogame consoles, and video rental services are the main drivers of this trend, with Generations X and Y and Baby Boomers all increasing their OTT viewing.

In the 13-to-54 age group, monthly use of an alternative method for viewing TV programmes or movies grew by over one-third in a year, from 26% in 2010 to 35% in 2011. This includes content streamed or downloaded to view on a TV, computer, laptop, smartphone, iPod Touch, or tablet.

Monthly use of any digital service connected to a TV rose almost 50% during the year — from 13% to 19% — within the 13-to-54 population.

The study also found that a number of key metrics have doubled since 2010 for this age group: video viewing on internet-connected videogame consoles (from 6% to 12%); video viewing on mobile devices (from 5% to 10%), and use of a streaming video rental service such as Netflix (from 13% to 26%).

The report demonstrates the strong generational differences in OTT viewing; compared to Baby Boomers (ages 46 to 54), Gen Y (ages 13 to 31) is almost four times as likely to report weekly mobile video viewing (30% versus 8%), and they are twice as likely to watch streaming video weekly (56% for Gen Y, 28% for Boomers).

“The number of platforms that account for significant video viewing is approaching a dozen,” said David Tice, VP and group account director at Knowledge Networks, in a statement. “This poses a variety of challenges — in measurement, accountability, planning, and targeting. But every challenge contains an opportunity to find new efficiencies in reaching key audiences, adding relevance to ads. Video is increasingly un-tethered, but the core elements of the video experience, and the rich context it provides, remain remarkably intact.”

The study was conducted among 1,013 qualified respondents.