I called a friend of mine, and he said as far as he could tell, The
Dinner isn't available for sale. According to IMDb, the production
company was Acorn Productions. He found several film related companies
with this name, but none of them look to be the one that produced the
film. He also checked WorldCat and found nothing. Perhaps it was only
released theatrically and screened at film festivals?
Sorry, this isn't very helpful.