In Canada, first, if you are clicking on a video, a specific video, you are doing it “on demand”.
When it's done on demand, in principle, it should be covered by the contract between the artist and the producer.
That said, often, if you request a video, and then stop asking for videos, YouTube suggests videos to you and suggests other songs by the same artist, or another song by a different artist. At that point it's no longer what is known as on-demand service, but rather semi-interactive or non-interactive webcasting, depending on the term you use. You haven't asked for anything, but a content is suggested to you. Personally, I can't tell you whether there is compensation every time, in those cases.