They don’t get the same information. They likely do, but they can’t be 100% certain it is really you (with various pro privacy extending that is lowered). When you log in, the certainty is 100%.
Given the YouTube service, there’s lot the need to log in (I suppose maybe it is just the way I use it, but if for example someone sends you a vimeo link, would you log in to watch it?)
They don’t get the same information. They likely do, but they can’t be 100% certain it is really you (with various pro privacy extending that is lowered). When you log in, the certainty is 100%.
Given the YouTube service, there’s lot the need to log in (I suppose maybe it is just the way I use it, but if for example someone sends you a vimeo link, would you log in to watch it?)