LONDON: Short-form mobile video creative of about six to eight seconds delivers on average 36% higher engagement levels than long-form, and it also delivers the best return on driving traffic, a new study has found.

Opera Mediaworks, a mobile ad platform, analysed campaigns by ten leading brands in the EMEA region, including those from eBay, automaker Mitsubishi, Stella Artois beer and TomTom, the navigation aid.

Aspects such as engagement and dwell times were compared in order to discover best practices for advertisers looking to engage mobile audiences with video campaigns.

While 36% higher engagement emerged as the average across the campaigns, the study found a six-second ad used by Stella Artois, as part of its sponsorship of the Wimbledon tennis tournament, delivered 60% higher engagement compared to a 15-second version.

In addition, short-form video attracted 25% longer dwell time than its longer-form counterpart, leading the report to conclude that short-form video is the most effective for branding campaigns.

However, when it came to product-focused campaigns featuring a call to action, the study found that video ads lasting between 15 and 30 seconds delivered engagement rates 30% higher than shorter form content.

For example, a Unilever Lynx campaign aimed at driving users to click a "Locate Store" button saw a 38% increase in clicks for the long-form video compared to the short-form version.

And a product-focused campaign for TomTom, which encouraged people to click onto a microsite, saw long-form video of 15 seconds deliver a 62% increase in engagement.

"It has long been suspected that the length of mobile video creative has a direct impact on audience engagement rates, and it's reassuring to have a specific measure of this now," said Mark Slade, managing director for EMEA at Opera Mediaworks.

"Mobile video continues to be a huge growth area for advertising, considering the ubiquity of smartphones and the changing habits of how we consume content," he added.

Finally, when it came to dwell time and click-through rates, the study further found that between 14 and 15 seconds is the optimal video length for maximising audience engagement in non-native environments on mobile.

Data sourced from Opera Mediaworks; additional content by Warc staff