Danielle Marshak, Product Manager at Google, posted an absolutely outstanding video on how video key moments work in Google Search and how to get them working for your videos. While the details on the implementation are not new, they have been in the help documents - for months, the video walkthrough is new and it is done super well.
Here is the video:
The video goes through what are key moments. It also explains how to enable key moments automatically and that Google identifies these automatic key moments using speech recognition, optimal character recognition and even visual signals and using seek markup. When you want to choose your own key moments, Google explains how to use Clip markup and other third party platforms description fields, like YouTube.
Watch it if you do a lot of work with videos.
Forum discussion at Twitter.