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Prop 8: The Musical, created by award-winning Hairspray composer Marc Shaiman, features stars such as Jack Black and John C Reilly lampooning backers of the constitutional amendment, which limits marriage to a union between a man and a woman.
The ban was passed by voters during the November election, five months after gay weddings were legalised in the nation’s most populous state.
A number of legal challenges are seeking to overturn the amendment, which was opposed by Hollywood heavyweights including Brad Pitt and Steven Spielberg as well as President-Elect Barack Obama and California governor Arnold Schwarzenegger.
Its passage sparked protests nationwide.
Prop 8: The Musical, directed and staged by Hairspray director Adam Shankman, features well-known stage and screen actors taking part in a Sacramento community college threatre group production.
It opens with the colourfully-dressed “California Gays and The People That Love Them” dancing and celebrating a “brand new bright Obama day” and “happy days for the gays”.
Then a black-clad crowd led by John C Reilly and Allison Janney describes how they will “spread some hate and put it in the constitution” via Proposition 8.
They claim the Bible says gay love is a sin. But Jesus Christ, played by Jack Black, intervenes to point out the Bible “says a lot of things”, including that shellfish is an abomination and it is acceptable to stone your wife or sell your daughter into slavery.
He urges them to “choose love instead of hate”.
The musical finishes with Neil Patrick Harris telling the Proposition 8 crowd about the “money to be made” from gay marriage before the entire cast unites in opposition to the ban, declaring that “gay marriages will save the economy”.
Mr Shaiman says in a note introducing the video that he is releasing the musical “six weeks later than he shoulda”.