This song is taken from the 1983 University of Waterloo FASS production called "FASS or Fiction". In it we see a very young Alyson Schafer (Alyson Knight at that time) as Dorothy singing a song to her dog Toto who in this retelling of the Wizard Of Oz is a giant fire-breathing dragon (don't ask).

Thanks to Brad Templeton for posting the full productions on his site (that's where this excerpt is taken from). (less info)