BRUSSELS: Video advertisers in Europe are choosing three main formats for their campaigns and PC/desktop continues to be the most popular device for serving video ads, a new report has revealed.

That is according to IAB Europe, which polled around 700 advertisers, agencies and publishers from across 31 markets for its inaugural Video Ad Formats survey.

The research found the three dominant formats across all devices in the European video advertising market are in-stream pre-roll, out-stream in-article / in-page as well as videos of 30-seconds' duration.

"These formats lead in terms of current usage, trends and ROI across the industry with little variation between advertisers, agencies and publishers," the report noted.

However, although PC/desktop remains the dominant device for video advertising in Europe, the IAB found advertisers and agencies in particular are looking to extend their communications to other devices.

More than four-in-five (80%), for example, increased their use of pre-roll on mobile devices over the past 12 months, according to the survey findings.

Advertisers and agencies are also turning to out-stream formats as they seek to expand across devices, and the survey revealed that more than half of buy-side respondents are using the in-feed format across devices.

Meanwhile, on the sell-side, publishers are also looking to out-stream formats, which the IAB said is a sign that they're aiming to improve the layout of their content and pages. For example, more than half are using the in-article / in-page format across all devices.

Elsewhere, the survey revealed that more than two-thirds of agencies are continuing to use the 30-second video format across all devices despite evidence that short-form is gaining in popularity.

A report from AOL at the end of last year found the volume of short-form video watched in the UK increased by 50% over the previous year and the trend was particularly pronounced among younger viewers aged 25 to 34.

Separately, a number of leading brands in Asia, including Netflix, recently reported significant lifts in ad recall after running campaigns that featured six-second ads on YouTube.

Mark Melling, Director of Video, EMEA at AOL, picked up on the finding that 30-second ads continue to be so popular among European advertisers and warned that shorter ads are better for driving affinity and purchase intent.

"It's not surprise that 30-second pre-roll ads are so high on advertisers' lists given it's the easiest way to put TV ads into digital," he said. "But we as an industry need to be careful of simply taking the 'easy route' at the expense of user experience."

Commenting on the efficacy of 30-second ads, he added: "Our own video creative research shows that where 30-second ads drive highest recall amongst consumers, it is actually 15-second ads that drive highest affinity and purchase intent.

"This means that if completion rates are advertisers' KPI then the shorter the length of the video the higher the completion rate."

Data sourced from IAB Europe; additional content by WARC staff