I've seen fighters pull off the knee bar submission after taking a bunch of chingasos so much, that It's becoming the hail marry of MMA submission finishes. Brock Lesnar and Frank Mir's first fight in the UFC is probably the most famous example of the knee bar submission being a hail marry submission in MMA. Mir was getting his head bashed in before he slapped on the knee bar and submitted Lesnar. Check out this free MMA fight video from the IFL for another good fight that ends in a knee bar submission.
Jesse Lennox vs. Emry Bussade
Here's a free video instructional of one way to set up and finish the knee bar submission.
Check out this video of Nick Diaz pulling off a knee bar submission in
Learn how to do the kneebar submission technique with hands on instruction.