What controls the brightness of the MCDU display and keys?

What brightness does the brt and dim on the right side of the MCDU MENU button change?
The brightness of the display, the keys or of both?
And if only one of them, what controls the other?

EDIT: As shown in this video, the brigghtness knob turns just the display on/regulates it's brightness. What changes the brightness of the keys (They seem to be lit befor the MCDU is turned on)?

These buttons are to increase and decrease brightness of MCDU. Also, they are used to turn on and off the unit.

As explained here:

BRT AND DIM KEYS
Control the light intensity of the entire MCDU. MCDU power up is performed with the BRT key and MCDU shut down is performed with the DIM key.

And here:

Repeatedly clicking on the "BRT" (the top of the paddle switch) will switch the unit on and increase the brightness. The reverse is also true. Repeatedly clicking on the "DIM" (the bottom of the paddle switch) will decrease the brightness and switch the unit off.

• Is there some sort of warning between the lowest "Dim" setting and "Off"? I can see someone (me in particular - I like my dash display very dim), thinking "that's still too bright, let me hit Dim again" and turning the thing off because it's already at its lowest setting. – FreeMan Oct 30 '17 at 14:37

The brightness of the keys is controlled together with the rest of the pedestal via the "INTEG LT MAIN PNL & PED" knob on the lower pedestal below the capt ACP.