Last March, Oprah Winfrey appeared on "The Ellen DeGeneres Show" to grant one of Ellen's greatest wishes -- to appear on the cover of O magazine --and only ET was with the two talk-show hosts moments before Ellen's shoot!

Lady O greets Ellen before the shoot and thanks her for participating. Ellen returns the gratitude, pointing out that it was she who wanted to grace the cover of the mag that almost always has Oprah's image on the cover.

Ellen's cover appears in the December issue of O.

Watch the video for more, including when Oprah introduces Ellen to her dog Sadie!