This article explains how to repost a video on Instagram. The instructions apply to the Instagram app for iOS and Android.
How to Repost Videos on Instagram | Quick and Easy!
While you can’t repost videos directly to your Instagram profile, you can repost them as Instagram Stories and then add the stories as highlights to your profile. You can also record your screen or use an app like Repost.
Here's how to repost a video to your story and share it on your profile:
Tap the Share icon (the paper airplane) below the post.