The miners feared that they would have to break a 113-year tradition and cancel next year's gala, in July, because they could not find the money to pay for the brass bands.
Michael Watt, who runs an international television production and distribution company, had anonymously given pounds 60,000 over three years to keep the gala alive, but that ran out this year. After seeing the film, he called his friend Rodney Bickerstaffe, leader of the public workers' union, Unison, and said it had moved him so much he would back the gala for another year.
Mr Bickerstaffe said: "I am absolutely delighted that somebody who only has had a minimal contact with the North-east and who has not got anything out of it himself, is prepared to put up the money for a community festival of such historic importance. It is a marvellous gesture."
Mr Watt is in America but his praises were being sung in Durham by David Hopper, general secretary of the NUM for the Durham district, which organises the event. "He is a very generous man," he said. "To find sponsorship from a man from the other side of the Southern hemisphere without any connection with the North-east is marvellous - we owe him a debt of gratitude which is unrepayable.
"Every band that plays at the gala gets paid an allowance. The bands will die without finance. And we need to maintain that social side of the brass bands. Whoever did Brassed Off did their research well, because it was exactly like that in this region."
Since the closure of the pits, which used to provide financial support, the bands have found it hard to make ends meet. Some have won a lifeline from the National Lottery but the Durham gala both provided a coveted platform for the best bands, and some handy income. The miners made an appeal through the labour movement for funding, but not enough was found to guarantee that the show could go on.
After seeing the movie, Mr Watt got one of his managers to contact the organisers last week and tell them he would provide pounds 20,000 for next year. Mr Hopper thought someone was pulling his leg when he was told to ring a "Mr Christmas" for the money. He discovered that Carl Christmas had indeed left him the message, and the money was available.
Mr Cropper believes it could help to relieve some of the hardship locally, if only for a day. "Easington has four times the national average for suicides and they are young miners," he said. "There is supposed to be a feel-good factor but these lads, if they have work, are getting paid less than they got 15 years ago. There is destitution in the North-east. Mr Watt has taken the attitude of saying, `Just give people a chance'. He has provided an inspiration, which is what the gala traditionally is about."
The gala's organisers hope that in July, they will have the first Labour Prime Minister attending it for two decades.