A smartphone with the logo of the Youtube video sharing website on the screen, in front of a computer screen showing the front page of Youtube.

Pop-ups, page takeovers, online ads that play automatically and commercials that interrupt someone's Spotify playlist: these are just some of the ways brands try to get consumers to notice them.

One of the most popular forms of online ad format is the "pre-roll," which plays before a video, and can be skipped after a certain amount of time. Brands are expected to double spending on digital video by 2020 to around $17bn in the U.S. alone, according to a report from IPG Mediabrands' Media Lab out this week.