I do not know where the artist acquired illegibly perplexing writing style for the trailer that communicates the story; nevertheless, extraordinary cinematographic intellectuality, counterbalancing indecipherability, transcendentalizes intercommunications’ incomprehensibleness.
Prepare to be disappointed.
If you freeze frame the video you can see the socket block failed and the rig came out of the arm because when the arm angle matched the mounting position, it slid out.
The arm broke of because he let he gear get away from him. The weight increases exponentially when you move the rig away. When you operate from a vehicle and the arm is connected to a mount you don't feel the strain of the arm and can accidentally allow it to "walk away" thus causing the arm to fail and break. To prevent this op's will tie the sled down and limit its travel.
This actually happened while filming The dark knight when the arm broke off due to the weigh of the imax camera while filming the opening bank robbery scene. However that was not op's fault the weight of the camera was just too much.
In this instance, purely operator error.
If you really would like to learn about creatively moving the camera here is a link to the master of this, Larry McConkey. Watch the shot and then watch the commentary.
I cant say much about the RED line and their controlled experiments but here is a real life situation: