[EdTsft]

YouTube is very convenient for hosting and sharing recordings of talks. You can't put a video recording in a mailing list or a paper journal, and journal/conference websites are generally not in the business of hosting video recordings.

Often it's much easier to understand another's research in the form of a presentation than a paper (papers give you the details but not necessarily the high level story), so, like it or not, YouTube is a significant scientific repository.