Another new feature recently added to Canva lets you record a video with your webcam and insert that video into any Canva design including presentations and social media graphics. In my limited testing of these feature it seems that you can layer video over background images and adjust the transparency of your video itself. To record a video with your webcam in Canva just head to the "uploads" section in the Canva design editor then click on the "record yourself" button. See my screenshot below for details on where to find the video recorder in Canva.
The option to record audio without video could turn Canva into a good tool for students to use to make narrated slideshows without having to use a video editing tool like iMovie or WeVideo. The new option to record a webcam video in Canva could be useful in adding personal messages to graphics like digital greeting cards or to slides to provide an explanation of charts and graphs.