It's how all union negotiations work, the membership will see it once it meets all the approvals from the election committee and boards and such. It's to keep the employer from picking away at the membership by offering one concession here or one there, and then letting the rabble be like "well actually that one point is pretty good, maybe we should just agree now!"
Now that said, I'm also going to wait before I'm convinced the strike is over. I'm pretty confident the agreement they are about to finalize and eventually present to membership is a good one, as the current mood among workers from all sectors is to stop the bullshit and get what they want. I don't think the membership will vote for this contract unless it's like 90% of what they asked for the first time. And that's good.
I say this as a film carpenter who has been working on and off and who expects to be fully unemployed by the end of this week, regardless of if this agreement gets ratified. We need the actors back too before we can continue working.
Lazlo?