I have a Waltham movement (s/n 18922948) that I have taken apart and cleaned.
I am in the process of re-assembling the watch and am up to replacing the train bridge. I have watched that portion of the video several times now, and have come to the conclusion that Bob has all of his watches trained to automatically fall into place on command. 
I cannot get all 4 gears to line up so that the bridge will go on. This particular bridge covers the center wheel, the third & fourth wheel and the escape wheel. The wheels always seem to fall just enough to keep from meshing completely and the stems going into the holes in the bridge.
Are there any tips or tricks to make this work better? I have tried to move the center wheel so the gears mesh,but this only seems to make one or more move to the side rather than spin in place.
Any help is greatly appreciated.
Thanks for your time!
Jimmy