You can only create video clips from detected events in the video history. You can’t create video clips from footage with no activity. Hopefully Google changes this when they make the promised updates to the Google Home app this year.
This is a real issue. As a Nest Aware subscriber with an older wired doorbell this feature was the main reason I chose Google (Nest) when recently purchasing a couple outdoor cameras. Google is less than transparent that I can only save Event videos. (If that's all I wanted.. I would have considered Arlo or Ring).
This issue is quite ridiculous. Almost everything important that happens on my cameras is not tagged as an 'event'. Is there any reason we can't record clips of what we actually want? Why does google continue to make the software worse than it was 5 years ago? Is anyone paying attention to major issues like this?