Being able to add a link to an IGTV videos used to be limited to business accounts. But now, Instagram will let all its users share IGTV videos on Instagram Story. You just need to tap on the paper airplane icon and it’ll show you an option to “Add video to your story.” Your followers can just tap on the preview to watch the entire video in IGTV. The feature works similar to how users can repost stories they’ve been mentioned in.
Source: The Verge