Richard,
This is one of your best videos, and after watching it, the light bulb finally went on for me on this double double quote paradigm.  The key for me was to understand in writing code for your expressions, you have to use SUBSTITUTION.  
It's like making ampersands (&) appear in a title for a form or report, you have to DOUBLE the ampersand (&&) in the caption box, which allows for one ampersand to appear in the title! (For example, to write a title for your Sales & Orders report, you have to enter Sales && Orders in the report caption line of the Property Sheet. I already knew that trick about ampersands && titles--See what I did there?--but I didn't put two and two together for quotes in expressions.  Now I get it!!!  In sum, you have to use SUBSTITUTION and use double double quotes ("") for a single double quote (") to appear and work in the expression.  
Light bulb on!!!
Thanks for the great video!
--Kent J.