Chrome Version: 72.0.3599.0
OS: macOS 10.14

What steps will reproduce the problem?
(1) Open the Harmony cast dialog (chrome://flags/#views-cast-dialog)
(2) Cast a tab
(3) Try to enable "Smooth motion" (e.g. to cast a video)

What is the expected result?
This option exists.

What happens instead?
The option does not exist and video playback is hella choppy.