Be careful with the Brasso. It uses a rather harsh abrasive and if worked too hard, will do more damage than good. Plastic and/or modern auto polishes (acrylic based) are better... their abrasives are made for plastic.
Just remember to use a soft cloth and do it lightly... ie, not all at once. Also use small circles and push outward to the edge of the disc... like spokes on a bicycle tire.
In the end, if you can see holes in the scratched area when you hold it up to the light... the data is already gone. Error correction proggies are your best recourse other than purchasing the disc again if you want a 100% copy.