Are you expecting someone to list the differences between a C4 and a C6? It all depends on how you look at it:
Similar: both are 3 speed automatics
Different:C4 is smaller and lighter
Similar:Theory of operation
Different: Details of operation....
C4: two multi disc clutches , two bands
C6: three multi disc clutches , one band
I guess if you understand how to do a C6 from your video, you should also be able to do a C4, but you still need to sweat the details,like torque values, clearances, etc.