IMO, Cathe's Wedding Video is the best place for one to start when becoming acquainted with Cathe's step tapes.
I also was doing Firm videos almost exclusively for years before I started off with Cathe's Wedding Video and was able to do the entire tape at once with only a couple of rewinds, and I'm definitely not one who has been able to catch on quickly to more advanced choreography. The higher impact moves in this one are in the last section (where she introduces the ricochet), but the steps are fairly basic in comparison to her more recent tapes (so I've heard). Cathe is an excellent cuer and breaks down the movements in The Wedding Video so a newbie can catch on fairly quickly.
The intensity is up there in the last section however, so I don't think someone who is a true beginner to exercising/stepping could do the tape without modifications, rewinds and maybe even stopping before the end, I think that's probably what Paula Z meant.
I've heard some recommend other starter tapes to those new to stepping (like Kathy Smith, etc.), but I went directly from the FIRM to Cathe and had no problem and have heard others that do the same. After I purchased The Wedding Video I bought Mega Step Blast and Step Heat, which were perfect for me to be able to learn those more basic step moves. I also have Rhythmic Step, but I'm waiting a little while before I attempt that one.
Good luck, I think you'll do great with the Wedding Video (the toning section is also a good addition) and it will give you a good starting point. I'll bet you notice that you catch on quicker that you thought you would!