YSK: that you can YouTube videos without being intrurpted by adverts. If you skip the video to the end, hit the replay button that should restart the video without any adverts.
from /r/YouShouldKnow
YSK：你可以在不被广告侵扰的情况下观看YouTube视频。如果你跳过视频到最后，点击重播按钮，应该重新启动视频，没有任何广告。