Thank you, I needed that. I've been dealing with a crashy computer today (non-Vegas related) and watching that took me back to the days of Photoshop on UNIX in the 90's.
I had a co-worker back then who never got upset with a crash. His response was always, "It's a miracle it works at all."
Didn't Adobe add multiple undo's in 2010 or something? :) I don't use Photoshop but I remember there not being multiple undo's for quite a long time. So long infact I dropped it and became proficient in Gimp before they added them.
Photoshop got the history palette around the late 90's or 2000. Photoshop does not do multiple undo via Ctrl+Z like many/most other apps but has the history palette mechanism instead with a different shortcut to linearly walk backward.