I believe this just means that the AV switch is in series with the W LED, that is to say that if you're utilising that LED then the AV switch will light up
That is a different option (In series with W LED). From the sound of it, he picked the dedicated to AV switch option.
This is one of the options that I am considering myself. From Emory's video description, the only downside is that in order to make white/silver color you have to mix the other three colors (RGB).