http://www.smh.com.au/entertainment/movies/mark-hamill-at-the-sydney-opera-house-20121121-29q7p.html

Mark Hamill explains the story of Star Wars
Once upon a time in a galaxy.....no-one knew what Star Wars was. Mark Hamill, who played Luke Skywalker, tries to explain it in an interview at Sydney Opera House, which is celebrating its 40th anniversary. Footage courtesy: The Opera House Project.

It was filmed not long after the movie was released in 1977.

Interesting take on the later films.