If you have scratches on you dvd's experience jumpy pictures/poor picture quality, or any console game on a disc e.g. Playstation, XBox, Dreamcast, etc, i've always found that if you spray on a little...
If you have Nintendo N64, Super Nintendo SNES, or any of the Gameboy games cartridges that do not work, clean the electrical contacts on them using an alcohol based cleaning material cotton bud. Leave to dry...