this is the first I have heard of this medical certificate... What is the deal with that?
Last time we dived at the Red Sea (Dahab) was 2007, but it was kind of the same as anywhere else -- that is, it depends on the dive operation.
Just in case, each of us just got a one-liner letter/certificate signed by our family doctor (U.S. Embassy doctor, actually, where we were stationed in Europe), stating that "This patient has no contraindications to scuba diving."
The dive operation (Sinai Divers) never asked to see the letters -- or maybe they did -- but I believe we did have to fill out the top part of the standard RSTC medical statement when we got there:
http://www.wrstc.com/downloads/RSTCMedStatementGeneric.pdf
It was the same drill with the other dive operation we used prior to that, Extra Divers in Makadi.
Be careful when/if you answer any of the questions "yes," because, like anywhere, the dive operation may require your doctor to specifically address the issue -- either in the signed letter, on on the bottom part of the statement. *edit* Just like Red Sea Shadow wrote.
If your family doctor isn't familiar with scuba contraindications, the RSTC statement gives an outline of condition that may be or are problems.