Since I haven't seen one at all, here it is. If there's already one that didn't appear both times that I searched the boards, then forgive me and please lock/delete/beat the n00b with a stick/whatev.
Anyway, post up whatever sweet SMB YouTube things you can find, or those that you have made yourself. I'll start off.
Super Mario Bros. 1http://www.youtube.com/watch?v=4taJq-7w6B0 - Level 1-1 played backwards.
http://www.youtube.com/watch?v=bI3p-l5GoAE - Level 1-3 played backwards.
Super Mario Bros. 2http://www.youtube.com/watch?v=WZH5u60VJV0 - Samples of Game Genie codes.
Super Mario Bros. 3http://www.youtube.com/watch?v=ZrHgZdsn6yM - Using the shoe in underwater levels.
http://www.youtube.com/watch?v=o2-cTYdpzWs - Samples of Game Genie codes.
Super Mario Worldhttp://www.youtube.com/watch?v=9MAFYJini2Q - Shows off the Test Level. (If the TMK crew wants to use this video on the site itself, they have my permission, since this does belong to me.)