Largest let's play on YouTube?

By this question I mean what Let's Play on YouTube has the most players/commentators on it - I know most LP's feature about 1 (the solo players like Pewdiepie and Tobuscus) to 6 (e.g. Achievement Hunter) or 7 (e.g. The Creatures) so I'm just wondering if there was a Let's Play where more than one gaming channel has crossed over with another and there are 10+ or even 20+ people in the Let's Play who are All commentating

Where I got the idea from (if you want clarification) - I was just thinking about how cool it would be if the following players got together for a large Let's Play (either a standalone video or a series) in Minecraft, GTA V, Smite, League of Legends, or any game that features servers that can accommodate a large amount of people:

*Markiplier (and his friends Bob, Wade and Yamimash)
*The Yogscast
*Pewdiepie (and his friends Cry and CinnamonToastKen)
*Mangaminx and Ohmwrecker
*The Creatures (ImmortalHD, Uberhaxornova, SSohPKC, Kootra, Danz, SlyFoxHound, Spoonerism)
*The Derp Crew/The Bros Angels (ZeRoyalViking, ChilledChaos, GassyMexican, Utorak, GoldGlove, EatMyDiction, Renaynay, GaLm)
*Achievement Hunter (Michael, Gavin, Ray, Ryan, Geoff and Jack with friends Caleb and Kerry)
*SmoshGames
*TobyGames

I'm just not sure if this feat is possible to do (I understand timing issues are a problem but the more worrying concern is if having a lot of people commentating and stuff is actually going to work)

Not 100% sure but AH is the largest that i know of. Also sometimes Lindsay plays with them.