I don't like that for self-defense but it's only because I don't know the context so I'm probably reading too much into it. But here's what I think I'm seeing.
1. If that was an exercise for self-defense, then I wouldn't do it in the cage, because then the cage can be used to protect the back. It limits the approach of the attackers. It skews the effectiveness.
2. On the streets you don't want to be pinned up against the wall when facing multiple attackers. Circular walls aren't the same as linear ones. With linear walls, the natural attack response for many is to prevent the person from running left and right. For example, play a game of tag and start with the defender against the wall. What you'll notice is that people will naturally try to prevent the person from escaping left and right so that they are forced to travel the center. When that happens, the person gets attacked from both sides.
3. Poor attack strategy. They were both attacking the same person but, they weren't working as a team. This is probably due to their training getting in the way. Had they thought more like street gangs, then #2 would be the most likely strategy. They would block off your left and right movements. I think the attackers in the video would have eventually reach #2 logic had the wall been linear. I also think being in regular street clothes and smaller gloves would have also help to get them out of the "ring mindset"
Just like I don't want to train a single leg defense off a crappy shoot. I don't want to train self-defense off a crappy attack, unless I was a beginner. Then I would need things to be at a slower pace until I can get better.
