Right, after carefully reading your post it seems you may have to rip the centre conse out again.
I can't seem to see the bit where you wired up the reverse camera impulse signal cable.
The pioneer should have a wire labelled "Reverse" and this wire needs to be connected to the reverse light so it gets a power signal to tell it that the car is in reverse and switch to the camera. Without it, I am guessing that the signal is overriding other video inputs, since your music is still playing.
I also have the eBay cam connected to a a pioneer HU
Hope this helps