Sure what were looking for is reliable sources That means were looking for guarantees of reliability in the source like having been published in an academic journal Further we want to avoid sources that represent only one persons view on the topic since were obviously not going to have a paragraph on everyone whos ever said anything about Hamlet What youve added isnt backed up by a reliable source since from that YouTube video we have no idea who this person is why hes talking about Hamlet or if anyone else believes what hes saying Thats why we want to see academic journals Even if his ideas are published in academic journals wed want to see citations to that work to determine that its sufficiently notable for an encyclopedia and not just one persons view