Med time people from other non-union locations. It's been reported the scabs are getting a higher rate, hotel, and other per diem benefits. On top of bringing in green people who haven't done a horse tumble.
Hungry actors from the country who didn't make it big in Hollywood?
Seriously though, I'm actually kind of interested in how much training and OSHA and insurance there is in this business to start with.
As for OP, you can do a bunch of things to support their strike, probably. Tell people you know this is happening and why it's a problem, leave the business a review on Google about it with whatever rating you desire, email the union and donate to any strike fund pool they might have. Even an hour of your wages/time spent helping them out will likely be of greater value than the percentage of the ticket price they would have received from you. And I'm sure they'll be excited to know someone other than themselves cares enough to do something to support them.
Edit: and you also get to show your kids how to constructively collaborate on solutions to social problems. Which would probably be cool for them to see too.