"In the beginning was the pun." (Samuel Beckett, Murphy).
This video is one of my all-time favourite things. I love the song anyway (listen to the versions by Smokey Robinson and the Miracles and The Beatles now, go on). Combine it with classic Seseme Street and you're already on to a winner. Add to that an extremely silly pun (in the days before txting!), and the presence of Smokey himself , and I can't really describe how much joy this video brings me.
Best of all perhaps are all the youtube comments from ex-terrified children, recounting being driven to horrible nightmares by the thought of this giant flying letter stalker. I really wish I could have been in the meeting when they thought this up.