So much for marketers' presuppositions: The much pooh-poohed 30-second pre-roll online video ad - when coupled with a display ad - is the best way to drive awareness in an online campaign, according to a study by the Online Publisher's Association (OPA) and Online Testing eXchange (OTX), reports MarketingCharts.

Moreover, 30-second spots are most effective way to get across brand "likeability," writes MediaWeek, citing the OPA study, "Frames of Reference: Online Video Advertising, Content and Consumer Behavior."

The OPA study exposed 1,422 online video users to video content and advertising, then captured the attributes that most impact awareness, ad likeability, ad relevance, and brand consideration.

Among other key findings, according to OPA:

• In two of the four advertising and brand metrics measured, ad length was the leading factor driving lift: 30-second ads outpaced 15-second ads for ad relevance (30 percent lift using 30s) and brand consideration (23 percent lift using 30s).
• The study reinforced the notion of a "halo" effect from website video content affinity: If the consumer had a prior brand affinity toward an advertised brand and liked the adjacent video content, brand consideration jumped 61 percent; but even if the consumer's initial attitude toward the brand was neutral or negative, brand consideration still rose 21 percent if the consumer liked the video content.
• Static companion ads can play a valuable complimentary role: To lift brand awareness, the combination of a pre-roll and a companion proved the most effective.

MarketingCharts provides more findings from the OPA study.