With Canon's EOS Utility software, you can connect your Canon DSLR to a laptop via HDMI and:
- control focus and zoom (if you have autofocus lenses),
- start and stop video recording,
- white balance,
- see RGB histograms
I can't find any mention of similar software for Nikon. I have found plenty of tethering software, but they do not use HDMI and are not intended for video.
Essentially, I am looking to duplicate the function of this item using a laptop: