How does TubeBuddy generate a video CTR?

Hey HN, I'm very curious about how TubeBuddy's "Click Magnet" https://www.tubebuddy.com/clickmagnet determines impressions and therefore Click Through Rate for its users' videos.

Through the Youtube Data / Analytics API, there is no way to view the impressions of a video, and as far as I can tell this is intended. My guess is that they use their chrome extension to scrape the Data, but I'm fairly sure this goes against Youtube's Scraping policy https://developers.google.com/youtube/terms/developer-policies .

I'm looking to implement this feature in my own application. If anyone knows something I don't, or can comment on the legality of it, I would really appreciate it.

Thanks!