There's ample evidence online video (both streaming video viewed through a browser and the expanding market of downloadable portable video) is a compelling medium and is a highly effective way to reach people.
According to Matt Pasternak of Klipmart Corporation, online video ads are "up to four times more impactful than other online formats, with the majority of viewers watching over 70 percent of the content." Pasternak also claims ads watched online are more effective at boosting brand awareness and purchase intent than the same content on TV. (Source: ClickZ Network)
According to analysis of Dynamic Logic's MarketNorms® database, online ads using audio and video achieve a greater impact on Brand Awareness at a lower frequency exposure frequency than other standard online ad formats. In fact, exposure to audio/video ads increases Brand Awareness by 10.0 percentage points.