Salut, Tonya. I don't have any experience with youtube vids or doc's to Gcast. I think you could add a YouTube feed to Netvibes, though. Here's what I am doing:
1) Each of my students have their own Gcast account. I didn't want to have one account for the whole class with one login and password - not enough accountability.
2) I played with this in the fall, and have found a system that is mostly working for me. I assign one speaking assignment at the end of each chapter.
3) I have set my browser homepage to my Netvibes page. I made a tab and called it "Student Podcasts" and then set up the feed for each students' podcast. I color-coded them by class. (Screen shot is attached.)

Have you thought about perhaps having your students set up blogs, and then they could embed YouTube vids as well as audio feeds, as well as their own text.

Hope that helps - let me know if you have any questions or think of anything else.