The Stripped program was owned by Clear Channel. They used to be on
http://strippedmusic.com - I don't know what really happened to them, it now redirects to iheartmusic.com and you can't find the performances. However; I have a trick to find the old stripped performances. Just paste the link below in your browser:
http://www.strippedmusic.com/arch_LASTNAME.html
then put the last name (if it doesn't work, try full name) of the artist instead of the bold text and click enter. It will take you to their archive of that artist. It worked with me with other artists as well, except for Katy .
I found Katy's stripped performance of "I Kissed A Girl" on YouTube:
http://youtube.com/watch?v=MjsaJmSn3sc