Really quick, I want to clarify something. This isn't to say that people who buy Christian things are idiots. What people buy is a form of self-expression. It's a matter of identity. Some people are proud to say they are Christian and will buy personal items that reflect that. Home decorations, music, that DDR knockoff that uses Christian bands, whatever, it's no different than my buying habits for Pokemon related items and such, the only difference is the subject matter. So, no, I'm not saying people shouldn't buy Christian stuff. If you like it and want to show it off to the world, that is your God-given right.
Yes, that includes things like the workout videos by Donna Richardson. Donna Richardson made Christian aerobics videos. They must have sold pretty well, given that she kept making them. However, Richardson got her start as one of the hosts of a show called ESPN Fitness Pros, which, like the 20 Minute Workout and the workout tapes by Cindy Crawford, Kathy Ireland, Elle Macpherson, and Ginger Lynn Allen (yes, she really did make one, and it pretty much went the way you think), realized there was sex appeal in seeing people with great bodies in tight clothing (there were some great shots of Richardson and the other girls in thong-backs. Oh yeah, aerobics gets your heart rate up, all right). I would think that would kind of make her videos a tougher sell with the Christian crowd (and, in addition to, on top of that, would indicate that Richardson is just capitalizing on a market, there's no personal faith involved), but like I said, they kept making new ones. So it was either forgive and forget or pay no attention to her past.
Where I have a problem is when these things are made and bought under the claim that it is so Christians can live "without compromise." Some people making these items and people buying them are doing it because they want to have or experience these things, but the Real World versions are somehow tainted. So here's a pure alternative, enabling you to do whatever without those icky counter values. It's substitution, that's all. And it doesn't stem from "I am a Christian," it stems from, "Christianity is superior, and not only will I refuse anything that doesn't promote that, but I will support the most trivial things that have nothing to do with it but reaffirm my personal bias." It's not identity, it's discrimination.
I don't do yoga. I tried it and, in a fit of "This ain't so tough", nearly fractured my ankles (I know, I know...my doctor didn't believe me, either). But yoga works for lots of people (the genetic dividing line seems to be you are built for power or for flexibility). But did you know there's something.... EVIL about yoga? Yoga postures are actually offerings to the 330 million Hindu gods! They focus on chakras! Supposedly, 9 out of 10 Hindus say yoga is Hinduism! It is subversion!
So what's a Christian to do? Why, you can have all the benefits of yoga without affiliating yourself with a false religion! "Here's PraiseMoves (r) -- The Christian ALTERNATIVE to Yoga!" (sic). The web page asks rather rhetorically, "Are you looking for a way to Get Fit WITHOUT COMPROMISE?" (Uh, I believe that's called "boot camp".) Basically, it's yoga with some slight changes to the postures and poses (if you've even casually followed yoga, you'll recognize the analogs of many of the poses) and different names, so you can do the thing without affiliating yourself with non-Christian religion. It apparently is selling and has a following, because it's been turned into a TV show on TBN.
If you want to wall yourself away from the outside world because your faith is so weak any outside belief will taint it, that's up to you. But don't act like you are part of some bold and glorious revolution. You're cowards, hiding away from aspects you can easily resist but you have no faith in yourself. God believes in you, why don't you?