As I understand it, and this is only based on previous conversations I have had on this subject with casino straff, MG casinos pay a % of their net take into a central pot at MG. I *think* this is around 10% but that would need clarification. I would imagine this is geared up to be proportionate to the number of progressives any one casino carries, but it may be a fixed percentage.
When a JP is hit, MG pay the money to the casino who in turn pay the player.
Further to this, my belief is that if a player spends $100 on say, Major Millions, although $20 of this will go to MG in progressive licensing, it doesn’t mean that that $20 is wholly contributed to the increase in the Major Millions JP alone. Instead, I would imagine it is aggregated exponentially along with all other progressive licence contributions across all the progressive slots. This would make sense as you would otherwise potentially find one JP crawling along much slower than it should.