Online video ads are most effective when they don't interrupt a viewer.  When consumers can opt in and choose the ad to watch from a couple options, they both appreciate and recall the ad more, said John Lowell, Starcom's SVP and director of research and analytics during a recent interview.

Starcom is working with clients like All-State and Capital One and sites like Hulu via its standards group, "The Pool," to gauge consumer responsiveness to a range of ads and ad formats across online video sites.

Lowell said it's important to remember that ad recall is not the same thing as liking an ad. "The ads that are most memorable aren't always most effective, so we need to find a balance," he said.

In testing a range of ad formats, Starcom has found that the context of where the ad is placed is one of the most important factors in whether it resonates with consumers. Someone might click-through on an ad, but click-throughs don't always translate into results, he said.

Daisy Whitney, Senior Producer