Video ads work more efficiently than image ads on Facebook in driving game app installs

"Mobile App Install (MAI) ads are often one of the most effective ad unit options for mobile gaming companies advertising on Facebook. Initially only supporting images, Facebook has now rolled out support for video—a content feature that has already driven higher CTRs for some Nanigans clients.
Like their image-based counterpart, MAI ads using a video asset also incorporate a great deal of functionality in terms of managing ad reach and viewability. But the question for advertisers is whether video is effective within the MAI unit."

Source:  Nanigans, 1st July 2015