Instagram just updated the app so you can start a video chat in Instagram Direct. You can pick one person or do a group chat.
Here's how to start vid chatting:
1. Open the app and go to the top righthand corner
2. Open Instagram Direct (the arrow that connects to your messages and mentions)
3. Click the plus sign icon in the upper righthand corner and then pick the user you want to call
4. In the lower right hand corner, there's a camera icon. Click it and it will call that person
To set up a group chat:
Same instructions above. The camera will turn blue, when you click it, you'll be added to the group!