• by Mark Walsh  @markfwal, May 30, 2012

More than half (52%) of all video watched on mobile devices is done at home, with viewership peaking during TV primetime hours, according to a new study by Frank N. Magid Associates commissioned by Tremor Video. People are also watching more than YouTube clips and sports highlights, with long-form video now accounting for 40% of video viewing on smartphones each week.

Online video consumption has increased 38% overall in the past year, and a 35% on smartphones.

Tablets, not surprisingly, are driving at-home video watching. The study found 85% of tablet viewers are using their devices while watching TV. People are watching about 8 hours of video per week on tablets compared to about 5 hours on smartphones.

What does that mean for cable TV? Some 8% of current mobile/connected TV viewers plan to cancel their pay TV service in the next year and another 23% are seriously considering canceling.

When it comes to video advertising, 75% of viewers have interacted with online video ads in the past month, with 58% demonstrating some level of ad effectiveness, including clicking on the ad, visiting a site or a store, or making a purchase. Two-thirds of smartphone viewers have engaged with smartphone video ads, and 71% of tablet users.

The Magid study was fielded between December 29, 2011 and January 9, 2012 with a sample of 1,010 consumers ages 18-54 who view video weekly or more on smartphones, tablets or connected TVs.