Sounds like a connection glitch.....
Go back to the Tutorial, right-click on it (
or the link prior to the actual Tutorial page that
takes you to it) and then select SAVE TARGET AS and SAVE it to some preferred location on your computer.
This way, you can view it repeatedly without interruption due to poor connection, as well as have it play in a different pane while you can work alongside it in BV real-time!
.