Although this video depicts what appears to be a scene in a psyche ward, it’s inclusion on this website is only to address how DID might appear from inside a person. The location and person could have been a multitude of other locations and people. Apparently, dissociation is very common in people — more than most would ever think. Dissociation can be normal and even helpful during trauma. However, some people have more extreme cases of dissociation depending on their past trauma.
A popular book about dissociation is STRANGER IN THE MIRROR. It explains dissociation in easy-to-understand language and gives examples of mild to severe dissociation. The book is for victims, survivors, their families, therapists and others. The related website is StrangerInTheMirror.com. Both the book and website have quick “screening” tests, which are not intended to be diagnostic — just screening tools.