As a person receiving the screen recording, do I have the option to opt-out, and not report my viewing metrics back to the creator?
As the viewer, you can't opt-out of analytics. The analytics are only identifiable as you (the viewer) if the recorder sends you the video through gmail as ViewedIt will append your email as a query string param to the ViewedIt link. If shared through social media, you'll still send analytics back so that the recorder knows how many views their video got, but you as the viewer won't be identified in those views.
If I'm creating a video, I don't want the people I'm sending it to to feel like I'm getting marketing data from them (assuming I'm not).