Instagram is an online mobile photo-sharing, video-sharing, and social networking service that enables its users to take pictures and videos, and share them either publicly or privately on the app, as well as through a variety of other social networking platforms, such as Facebook, Twitter, Tumblr, and Flickr. [source]
How to download videos from Instagram
1. Copy a supported Instagram url from your browsers address bar (see above for some examples).
2. Paste the url into the box above and click the Download button.
3. A list with several download links will appear. Each link represents a different video quality.
4. Choose a quality and click the download link.