I thought that the official Sesame Street YouTube channel had added some classic clips that aren't at sesamestreet.org, but then I saw that there's another YouTube channel with the name Sesame Street (there can be two channels with the exact same title?). I didn't even notice the lack of a "Sesamestreet.org" logo at first, but it through me off when I saw this three-part segment all as one video, with no fade-in/fade-out like on all officially-uploaded clips, no advertisement for sesamestreet.org at the end (which has appeared on pretty much every clip posted by Sesame Workshop in the past year), and saw a second of each following/preceding clip between each part.
I guess it doesn't matter, it just confused me a little. I would be surprised if Sesame Workshop uploaded inserts taken from episodes that have them (or maybe they do but there's no sign that they do. There are clips that start with the clapboard, and I think I've seen one clip that ended with a clapboard shot for the "Gimmie Five" number, but that wouldn't have been taken from an episode).