Officially, the Instagram app does not provide an option to download videos. But you can use the “Save” option (3-dot menu > Save) to save a video, which puts that post in your “Saved” section — but not for offline access. If you want to download a reel or video to your phone, you will have to use third-party apps or websites (like “Savefrom.net,” “InstaSave,” or “SnapInsta”). Just make sure that you save videos only for personal or non-commercial purposes and do not violate copyright.