Well, you do want to use ETTR with raw video, but you want to do it manually.
Essentially you want to make sure you enable raw histograms in your global draw, then as you're framing your shot you want to tweak your ISO and aperture to get you as close as possible to maximum exposure (e.v. 0), you don't want to go into - but you also don't want to be too far into the + either.
Your best bet is to experiment and then check your resulting files in Resolve or whatever you use for post processing, after a while you'll get the hang of it.