How do I record the sound that comes from my speakers, like audio from a YouTube video?

By default, Camtasia Studio and Relay can’t record the audio that comes out of your speakers.  It will only record the microphone input.  However, there are a few things you can do so that you can record both your voice and the audio from your speakers.

A very basic solution is to hold your microphone up to your speakers while your video is playing.

A more elegant solution might be using an audio splitter an a loop cable.  Read more here.