And, according to IMDb, Heath was in an Australian kids' movie called Paws in 1997 as a character named Oberon. The full movie is available on Hulu (also through a link on the IMDb page below).
http://www.imdb.com/title/tt0119870/
The name "Oberon" is a funny coincidence, since Merle Oberon's most famous part was in the 1939 version of Wuthering Heights, the filmed version of the book where Heath's name may have purportedly come from (Heathcliff).
Going back to
Paws, I've been watching it this evening, and it sucks, but you can skip the junk and find Heath in the following spots. In the movie, he plays the Shakespeare character Oberon, in
Midsummer Night's Dream. Sometimes he delivers his lines off-camera, but it's distinctly his voice. He definitely has a small part.
He first appears at 41:12.
Then at 55:53.