either there's a glitch with the site, or they're removing the ss clips due to copyright concerns maybe? the films i loaded are still in my profile, but don't show up when you do a "sesame street" search anymore.
you can view them here:
http://www.youtube.com/profile_videos?user=PiLfan
you can search for other users who posted a lot of clips and view the videos in their profiles as well.
hopefully, the site will be back to normal before too long.