CrowdTangle is a social monitoring platform that news organizations and companies can use to see what internet content is quickly gaining traction and going viral. Facebook offered free access to CrowdTangle to newsrooms earlier this year as a part of it's Facebook Journalism Project initiative to improve its relationship with publishers.
Why it matters: For publishers looking to capitalize on viral content, the metrics allow publishers to understand and analyze which pages and shares are driving views, something not previously offered to publishers who could only access top level metrics.
As a part of this rollout, Facebook is introducing a new video metric into its ecosystem: the the number of video views that are generated when a page shares someone else's video. This will be especially helpful in helping publishers understand which pages drive the most video engagement, although presumably the pages with the most shares will be the ones with the largest audiences.