How to track googleapis node media upload progress?

In their docs for google-api-nodejs-client, they say:

Every request to the API returns a request object, allowing you to track the request's progress or general information about the request.

But how do you really do that? for instance let's say I upload a video to youtube using:

var request = youtube.videos.insert({some: params},function(err,response){});

How can I use the request object to generate a -- let's say -- progress bar?