playback_based_cpm_usd - Effective cost per mille, or the estimated average gross revenue per thousand playbacks on which an ad was shown, independent of which specific playbacks the advertiser was charged for.

impression_based_cpm_usd - Effective cost per mille, or the estimated average gross revenue per thousand served ad impressions.

card_click_rate - The average card clicks per impression. This measures how often viewers clicked a card after seeing it.

card_teaser_click_rate - The average teaser clicks per teaser impression. It measures how often viewers clicked a teaser after seeing it.

click_through_rate - The percentage of clickable annotations that received clicks.

close_rate - The percentage of annotation impressions that were closed by the viewer.
average_percentage_viewed - Average percentage of a video your audience watches per view.