It's always awesome to see CodePen pop up in videos of presentations around the world!

Brad Westfall at HTML5DevConf 2014

And screencasts as well:

Martin Wolf screencasting

You're of course free to use CodePen in any capacity like this, and in any view you please, but we might suggest Presentation Mode for giving you a bit more screens pace and the ability to adjust things like font-size quickly on the fly.