In order to fully appreciate what exactly makes this ad "indecent," you really need to watch it in full (link embedded above). It's 30 seconds long, and basically shows women "of size" in their underpants.
In other words, the ad is quite literally exactly the same as every single ad for every single cosmetic and piece of apparel marketed to women, with one conspicuous exception: the women portrayed in the ad are fat (See Fig 2).
And naturally, that makes the ad "indecent." For your reference, here's the dictionary definition of "indecent":
in-de-cent (adj.): "not conforming with generally accepted standards of behavior or propriety; obscene; not appropriate or fitting."
Well now it all makes sense!
Fat chicks definitely do not conform to generally accepted standards of behavior or propriety. It is much more proper and appropriate to depict a size zero stripper in pasties and a black leather thong, suggestively pouring milk-shake/soap/paint/jizz/WTF-is-that-shit-even-supposed-to be all over her toned, tanned body to sell cheeseburgers for a fast food chain.
More acceptable, at least, than it is to show an "obscene" and "not appropriate" size 18 mother breast feeding her baby in underwear, with rolls of pasty white fat spilling over the waistband like pretty much any woman who has ever had a baby and/or worn underpants in her life has done.
Mothers: Hide your daughters, and yourselves. Unless you resemble Fig. 1 below, take note: you are fucking INDECENT, and network TV won't let you forget it.