Determining the Best VCR Metric for In-Banner Video Ads

Hello, Has anyone implemented a Video Completion Rate (VCR) metric for in-banner videos? I'm considering two different methods: 1. Video Completes/Video Starts In this approach, a 'video start' counts when the user has the banner within their viewport and the video begins. A 'video complete' counts even if the video finishes outside of the user's viewport. So, the video needs to be in view to start but doesn't need to be in view to finish. 2. Same as the first method, but the video must complete within the user's viewport. This means the entire video needs to be visible to the user for its duration. Here's an example scenario: A user lands on a mobile web homepage. The top banner has an autoplay (muted) video. The ad sticks as the user scrolls, and the video continues to play. The ad auto-dismisses after 3 seconds, but the video duration is 6 seconds. Technically, the ad remains at the top of the homepage, and the video completes out of the user's view. So, if the video finishes while still technically on the page, but the user doesn't scroll back up to watch it, should it still count as a video complete (provided they don't navigate away before it ends)? Any advice or insights would be greatly appreciated! Thank you!