"Butterfly Ball" by Roger Glover and Ronnie James Dio
I always remembered the clip as being really cute, but there was something about the song itself that I really liked even before I saw the clip. I didn't realise it was based on an existing kid's book though. In hindsight it makes sense, and the animation was clearly a tie in with the book.
"The Butterfly Ball and the Grasshopper's Feast is a concept album and subsequent live rock opera appearing in 1974 and 1975 respectively, based on the children's book of the same title."
Does anything say 1970s more than the term rock opera?! (Ok, maybe flares.)
* Sandie Shaw, "Puppet On A String"