YouTube on mobile devices currently supports gestures such as double tapping either end of the video, where upon doing so, users will be able to skip forwards or backwards in a video. However there is currently no gesture that will let users skip the entire video, save for the user clicking another video.
However according to a post on Google+ by user Joe Kelly (via 9to5Google), it seems that YouTube is testing out a new feature on Android which lets users skip an entire video by swiping. Note that this swiping not only skips the entire video, but the page as well where basically the entire page changes, including its description, like/dislike/share buttons, suggested videos, and so on.
As for which video will load, basically swiping will take users to the next video in the “up next” section. As 9to5Google points out, this makes it faster to switch between videos, whereas previously you would have to wait for the video to lad before the forwards/backwards buttons appear, but now all users have do is swipe left or right from the edge of their screen.
It seems that the feature is currently in testing as not everyone is seeing it made available to them just yet, so if you don’t see it not to worry as it means that the update has yet to roll out to your device, or you’re just not part of the test.