Actually, if you are just wanting to watch vintage classic Sesame skits, then there are quite a few around, and in some cases legitimately. if you have a good trawl through Sesame Street's official site: http://www.sesamestreet.org/home and in particular the "videos" section: http://www.sesamestreet.org/browseallvideos you may notice that quite a number of vintage skits do appear there (they tend to be labelled "Classic"). There is even a subsection on the site for Classic Clips.
You can also find Sesame clips on YouTube (some legitimately, some possibly not), that probably includes some vintage ones too.
You can also find Sesame clips on YouTube (some legitimately, some possibly not), that probably includes some vintage ones too.