Discs can heal. For those with DDD that are drying out, it may harden and stop leaking, and quit breaking down further, but it will not regenerate and restore itself back to "normal".
Can DDD be contained? Not sure what you define as containment. But there is no cure for DDD nor can you prevent it. But you can keep yourself and your spine as healthy as you possibly can to help keep your spine from further injury. Still no guarantee.
DDD happens to us all. It's basically the aging process of our spine. But for some it causes us pain and can also lead to trauma and serious spine issues.
With all respect to Cythren. I am sure she did not mean to say that disc herniations happen to us all and that DDD will make this happen. Disc herniations can be caused by many factors and does not happen to us all. DDD can indeed increase the odds for a disc herniation/bulge to occur, as they disc is no longer fully healthy when DDD occurs. But DDD does not automatically lead to disc herniations/bulges. I just want to clarify that to anyone that is new to learning about this and doesn't yet understand things overly much.
Hope this helps. Take care.