No videos but from personal experience Eddie B talked about observing JJM's game ALOT.
His takeaways were that even in the gi JJM used what some might call a no gi game. Without being able to fully grip on one hand that hand instead is used to hook, to clinch, to hug, to push, to pull.
Submissions piggy back of the same logic, he generally wasn't using gi chokes with missing fingers but all the standard no gi submissions still worked well. Armbar, triange, rnc, etc