This is footage taken from the Portal 2 Beta DLC provided to press outlets.
In this video you can see how to use the Steam Workshop, find maps, download and rate them once you've completed it. The dialogue from Cave Johnson seems to randomly run over custom maps you play, you can hear an example of this in the video (apologies for flickers in this section!)
I'll be posting up a video of me playing with the actual Puzzle Creator shortly, as I created the most anticipated chamber ever, titled 'Worst Chamber Ever'. Subscribe to our youtube to see it early!