"The movie file xxx.mov cannot be found."

I added B.mov file into A.mov by copying B and pasting it into A. However, I used 'Save' instead of 'save as'. I've deleted the original B.mov and now when i tried to open A.mov, Quicktime says "The movie file B.mov cannot be found. Without this file, movie cannot play properly."

I am not able to see A.mov at all in QT, but if I use the preview in Cover Flow, I am still able to see that portion which originally belonged to file A.mov while the 2nd half which was originally B.mov is a black screen. I understand that I may not be able to get back the 2nd half, but how can I at least retrieve A.mov since I can still see it?

I'm using Quicktime Pro btw.