If you want to build it yourself, here is the schematic I copied from my notebook. The only difference between this and the prototype is the op-amp. The prototype uses four single op-amps while I plan to use one quad op-amp in the finished product. This change saves money and board space.

Amiga RGB -> YPrPb Adapter Parts List

IC1 - LMH6722 Quad Wideband Op-Amp

C1 - 1uF 35V Radial Capacitor Tantalum

C2 - 1uF 35V Radial Capacitor Tantalum

C3 - 0.0047uF 50V Ceramic Capacitor

C4 - 0.0047uF 50V Ceramic Capacitor

R1 - 6.8kohm 1% Resistor

R2 - 6.8kohm 1% Resistor

R3 - 1.3kohm 1% Resistor

R4 - 12kohm 1% Resistor

R5 - 8.2kohm 1% Resistor

R6 - 3.9kohm 1% Resistor

R7 - 1.8kohm 1% Resistor

R8 - 5.6kohm 1% Resistor

R9 - 5.6kohm 1% Resistor

R10 - 75ohm 1% Resistor

R11 - 75ohm 1% Resistor

R12 - 75ohm 1% Resistor

R13 - 1.0kohm 1% Resistor

R14 - 3.0kohm 1% Resistor

R15 - 3.0kohm 1% Resistor

R16 - 3.0kohm 1% Resistor

R17 - 75ohm 1% Resistor

R18 - 360ohm 1% Resistor

R19 - 360ohm 1% Resistor

R20 - 360ohm 1% Resistor

R21 - 360ohm 1% Resistor

R22 - 68ohm 1% Resistor

R23 - 39ohm 1% Resistor

R24 - 220ohm 1% Resistor

R25 - 39ohm 1% Resistor

R26 - 130ohm 1% Resistor

R27 - 75ohm 1% Resistor

R28 - 100ohm 1% Resistor

R29 - 680ohm 1% Resistor

You can substitute the LMH6722 with another op-amp suitable for video (i.e. wide bandwidth). Something like the LF347 will not do because it's bandwidth is too narrow.