There are a couple of other names which keep popping up: Nigel Farage, Ben Shapiro, Jacob Rees-Mogg. None appear as often as Peterson. They have something in common with him though: They all hail from the right wing of the political spectrum[3]. The opposing perspective is conspicuous only by its absence.
They also provide a tool [eticlab.xyz] for you to check how many suggested videos you'd have to click on to reach one of mr. Peterson's.
The researchers are not suggesting a bias by YouTube nor foul play by Peterson, merely noting his remarkable predominance on the platform.