Instagram is testing a way for you to tag your friends in videos.
Tech Crunch writes:
Instagram is testing a way to allow users to tag their friends in their video posts, not just in photos, TechCrunch has learned and the company confirmed. The option works similarly to tagging photos, but instead of pressing the small icon at the bottom left to see the list of tagged names appear over top of the content – something that would be more difficult with videos – the button links to a list of tagged people.
When you tap this button, you’re directed to a new page titled “People in this Video” with all the Instagram users who have either appeared in the video, or who the original poster wants to alert in some way.
You can read more here.