The comments trait exists on video objects in ANS (https://github.com/washingtonpost/ans-schema/blob/master/src/main/resources/schema/ans/0.10.1/video.json) but there seems to be no UI for setting those traits on a given video in the GF admin.
Could controls be added to make it possible to turn comments on/off for a particular video, including passing those traits through to the Content API record for the video?