If you go to the middle/bottom of page four of my Darius Miniatures thread you can see I put my pigments on dry and flooded the fixer in after.

When applying them in a thinned, wash/filter like manner I will mix the pigments and fixer first and apply them together... but I do this very lightly and very subtle for soft effects.

When applying them into the running gear area I will either apply them dry and flood the fixer in, or flood the fixer first and drop the pigments on after. This way the pigments keep their in scale, rough texture and don't mix together into a paste (like in that video) which IMO... looks fake.

All these methods can work and achieve different results. It depends on what you are looking to accomplish with them.