Google-owned YouTube announced on Friday that it plans to phase out its 30-second, unskippable pre-roll ads by 2018. Many users reportedly find the format obtrusive, so YouTube is killing the 30-second ads but keeping 20-second clips that cannot be skipped, and its six-second bumper ad format. YouTube will also continue to offer its TrueView skippable ads, which do not come with time limits and only cost advertisers when the viewer opts not to skip them. The move is in response to the growing popularity of mobile video. “More than 50 percent of YouTube’s video views now come from mobile devices,” reports Variety.