@Christina VanHorn - Are you still having these issues with Stream today?
It sounds like you are having issues with both the your own videos that came from Mix and from the help videos we show when you log into Stream for the first time. If that's the case it almost seems as if there was something not quite right with your network connection or something. Have you tried again or from a different internet connection?
If you are still having this issue we'd have to get more information from you and see if we can troubleshoot. So sorry you ran into problems.