My problem was is that when I got a custom character and went into the physics asset, he went berserk and spazzed out everywhere. I found this tutorial however by Unreality Simon on Youtube, on how to set up the physics asset for your custom character. Here is the link: - YouTube
What was the solution to this issue? The videos you have provided no longer work. I am currently having this issue and I have yet to find a solution to it. My character also went crazy when simulating physics.
Thanks in advanced.