macOS High Sierra unable to natively play videos encoded with HandBrake's H.265 setting
High Sierra's H.265-capable apps want hvc1 instead of hev1. Handbrake's stable release as of now (September 26, 2017) does the latter. Nightly builds should do the former.

Relevant code change: https://github.com/HandBrake/HandBrake/commit/67dfaca7ac3ec56cc4ab3c7f9f60ab3b7c43a0db