Note: This calendar view maps the number of captures of https://accounts.google.com/ServiceLogin?hl=en&uilel=3&continue=https%3A%2F%2Fwww.youtube.com%2Fsignin%3Fnext%3D%252Fupload%26hl%3Den%26feature%3Dredirect_login%26app%3Ddesktop%26action_handle_signin%3Dtrue&service=youtube&passive=true, not how many times the site was actually updated.
Look Up URL in general Internet Archive web collection.