A sobel edge effect can be obtained here: Looking for a basic Sobel Edge Post Process Material? - Asset Creation - Unreal Engine Forums
I dont know which ue4 version it uses, so you might want to read trough it all.
As for the tutorial, its a good tutorial, it works.
The outline in borderlands isnt a postproccess, its the same model, slightly resized and the normals inverted + black texture.