If you can't make the training, this is the best tutorial we've found. This is a little long, but it offers a thorough explanation of how to use the Loom Chrome Extension. Tip: Watch it at 1.25 speed.
If using Chrome on a school account, you will see a small button on the top right-hand corner of your Chrome browser. From here, you simply choose whether you want to record your screen and camera, your screen only, or your camera only.
When done recording, the video will save to your library to be accessed at any time to be deleted, download, embedded , or shared in various ways.
Check out this post by the always great Matt Miller. Matt likens a screencast collection to a Netflix catalogue,
Netflix is like a library of videos at your fingertips. When students have created screencast videos and they look back through their work, it’s like Netflix for learning!
With Loom, a video library can be like a Netflix for learning. Or, embed a catalogue of screencasts on a page of your blog.
This post by AJ Juliani talks about screencasts being a necessary (and ideal) alternative to math homework in some cases.