I was trying to continue the Unity Live Lessons today when a problem occurred: all the videos are gone! Gone! I tried accessing it in Waterfox and Chrome, and on a separate computer, but nothing makes the videos show up. I need help so I can go back to learning!
Yes, your right, I think they are redoing for Unity 5, I read that some place, but done hold me to that.
I think I have then all downloaded, so if they don’t come back I can send you one a month. ha ha
that is a joke.
Joker renny
Yea I was really getting into unity and was on the 5th lesson and boom gone. 
All of the videos are there, but Unity has rearranged them into topics
You can still find them in chronological order on the Live Training Page as “Past Sessions”:
http://unity3d.com/learn/live-training