Above is a general video about the Rich Content Editor. 

The Rich Content Editor is the toolbar where you find often-used tools and features. You will recognize this rich content editor as it resembles the toolbar from almost any application that you’ve used. The Rich Content Editor in Canvas gives you access to the Media Recorder, which will enable you to record audio or video directly into your Canvas course wherever you see the Rich Content Editor. Which is virtually everywhere in Canvas. 

Below is a specific tutorial about the Media Recorder.