If you're looking to replace one of your existing YouTube videos with another, you can change the URL very easily. All you need is the URL of the new YouTube video you'd like to use.
In the Module, go to the Content tab and click Add and Arrange Content.
Once you're on the Arrange screen, click on "See Slide Detail" in the top right.
Now, the content will show each individual slide. Search for the YouTube video and select the slide from the left-hand side. After the YouTube slide has been selected, click the "Change YouTube URL."
Lastly, paste the new YouTube URL in the "Update YouTube Video" window and click "Done." The change will be instant and will autosave.