Weight paint not showing I having problems to see weight effect area in the viewport.

For example this file:
https://dl.dropboxusercontent.com/u/51093542/35-minecraft-char.blend (right-click and 'Save As' to download .blend file)

used in this tutorial: 

https://www.youtube.com/watch?v=rkT92aoMpP0

Compare how its shown in the video (around 5:23) and this


In another test if I pose the object and try to weight paint on it:


So obviously the weights are being applied to the object, I just can't see it like its supposed to do.
Any ideas?
The file you sent seems to work fine for me (Running Blender version 2.75a): 

Make sure "Custom Weight Paint Range" in the User Preferences under System is unticked: