Some media allow viewers to skip advertising after a certain number of seconds (e.g. 5" on YouTube and between 5" and 30"+ for in-app advertising). The amount the advertiser pays is usually based on how many viewers watch the ad for at least 30 seconds (or the full ad if it's shorter than this).
What this data from Dentsu suggests is that allowing people to self-select how much of an ad they view can be highly effective because 'voluntary' dwell times result in much bigger uplifts in brand choice than corresponding 'forced' view times. This approach might work well for an advertiser that finds it hard to target their audience accurately (and therefore tends to waste a lot of money reaching irrelevant people when using other forms of advertising).
A self-selection approach would not make sense for many brands because growth requires bringing in new people to the brand rather than preaching to the converted.
For a discussion of this topic, see this LinkedIn thread.
For more details, see this paper produced by Dentsu.