I've never seen a full melt down, but I remember a time when a CM really wanted to. We were at MK, and had just watched the first parade up at the wheelchair section in the front of the castle . We had seen wishes the evening before so decided to go back to Pop. However, the road was completely plugged with 15 year old girls sitting on Mainstreet USA waiting for the fireworks. I had had quite a lot of dealings with these girls, because there were about 500 of them at Pop. I have always found them respectful and helpful. I don't speak Spanish but I've found a smile and gentle manner go along way. Anyway, I asked the CM how to get through the crowd to get to the busses. I've seen times when they open the back way to exit when MK is extremely busy. He told me there was no other way to leave. He said he had been trying to control these girls since 9:00 am but they don't speak English. I expect some of them were pulling the "I don't speak English" card. Anyway, there was quite a crowd of people wishing to leave, and it could have been a dangerous situation. I was feeling a sort of panic, fearing the blocked road. The road was completely plugged with these girls. They were tired. They wanted to sit. They had found a good spot to see the fireworks and had no intention of moving. If I could have manuvered through, I could have gone through the shops but even that was impossible. The CM told me if I could squeeze through to try, but if not I'd have to wait until I could. He was thoroughly frustrated, and I'm sure very tired of the whole thing. So I gently asked the girls if I could squeeze through and they shuffled over enough to make room for me and my DDs wheelchair. As I made my way down Mainstreet the girls parted, and made room for us to get through. Perhaps they didn't want to be rammed with a wheelchair, but I would never intentionally do that. They all seemed like nice girls, having a great time in such a happy place. As we progressed, I'm sure a hundred people followed us through the crowd and were able to leave. I expect that the CMs then were able to keep this passageway open, but I didn't stick around to see.
In regards to post 33.
I have seen when Epcot was terribly busy, the CMs form a line and direct traffic keeping everyone to the right, to keep the pedestrian traffic flowing.