I think you've missed the way the wire is routed through the rightmost ferrite. I believe the wire starts at the rightmost jack, goes throught he middle of the ferrite, loops around it, where a tap goes out to the input jack, and then loops back in through the middle of the ferrite, continuing on to the left where it's connected to the tap on the other ferrite.
That loop around the ferrite just splits the signal in two, while maintaining an impedance match. There's a similar loop around the leftmost ferrite, and in the same way, it splits its signal in two while maintaining the impedance match. Thus, the left two output jacks get a lower signal level than the right output jack.
There's a DC connection all the way through, between all the inputs and outputs.