First things first, Instagram doesn’t have an open API. A client must be authenticated to retrieve users and their media. Luckily, the API does support JSONP, so we can create a front-end gallery with just an access token.
Instagram doesn’t allow a client to grab media by username, a user id is required. So, we have to chain a couple calls together, if we only have a username.
Warning: You really don’t want to float an access token around that doesn’t belong to the current user. i.e. Don’t acquire your own and hardcode it into your application.