Google just updated the Google Docs for Android app.

Collaborate and edit anywhere with the updated Google Docs for Android

This means that: You’ll see updates in real time as others type on their computers, tablets and phones, and you can just tap the document to join in.

The person in the video shown copying and pasting on a phone is a lot faster and accurate than anyone I’ve ever seen. I always have a bit of a struggle getting the right start and end positions.