The next time you take a screenshot or video recording from Instagram Stories, you may receive a notice like the one above. It is a new function of Instagram that will notify people who make image captures of our stories, and they will be notified as follows:
That is, we will not receive a notification alerting us that someone has captured the story in an image or video, but it will show a distinction of those who have done it, alerting us to it.
This feature is not implemented for everyone, but rather, it is a feature that Instagram is testing among some of its users in beta applications, and that they will eventually see the light of day in the final version.
What Instagram told Techcrunch was: we are always trying to improve the experience in Isntagram and make it easier to share any moment with the people that matter to you.
This feature closely resembles something that has already been implemented on Snapchat some time ago, so it wouldn't surprise me if it ends up rolling out for everyone.