I looked at your sample, and I assume you are referring to the banding in the gradients of the background? The shadows/blacks around her cheek and hair looks ok to me. My monitor on the laptop I am reading on is not that great, so I might be missing something.
Normally on my D5100, I pretty much stick to Portrait and Landscape for most shooting conditions. The Flat profiles I have loaded custom are not much better than shooting in a profile. Reducing Saturation and sharpening for a new profile has been the best I have found. You can add these back into the image in post.
You might want to try recording the HDMI interface as long as you can get a clean HDMI output. Then record to a ninja or Blackmagic intensity card to a 10-bit codec. Assuming the d7100 outputs 10-bit clean video pre-encoder to the HMDI. The 8-bit AVC codec in the Nikon, even with the high bitrate hacks, can cause a lot of banding and blocking in gradient darks. 8-bit only has so many steps between light and dark, and add on top of that compression artifacts.
You may be better off with a newer video device like a C100-300, Sony F-series, or an old RED ONE w/ Nikon mount. These devices will allow you to shoot in a s-log mode, and or codecs which will preserve your studio elegant gradients. Even RAW mode video from one of the Canon DSLRs would give you 12-14bit color gradients, but at the cost of greater post processing times.
Shooting in a Log mode you actually overexpose and then bring down similar to the way we used to shoot film.
Your editing application could be some of the problem too. Make sure all processing is done in an editor capable of 32-bit floating point mode, and not just 8-bit. Transfer all camera original to an intermediate codec like HDCAM SR/SR-lite, XAVC-HD, ProRes, or DNxHD/R. Then do your tweeking in 32-bit mode.
Nikon Profiles – https://www.nikonusa.com/en/Learn-And-Explore/Article/gu5zwt9w/Picture-Controls-Step-by-Step.html