WebDriver driver = new RemoteWebDriver( ... );
driver           = new Augmenter.augment( driver );
( (TakesScreenshot)driver ).getScreenshotAs( ... );

public class ScreenShotRemoteWebDriver extends RemoteWebDriver implements TakesScreenshot
{
    public ScreenShotRemoteWebDriver(URL url, DesiredCapabilities dc) {
        super(url, dc);
    }
    @Override
    public <X> X getScreenshotAs(OutputType<X> target) throws WebDriverException {
        if ((Boolean)getCapabilities().getCapability(CapabilityType.TAKES_SCREENSHOT)) {
            return target.convertFromBase64Png(execute(DriverCommand.SCREENSHOT).getValue().toString());
        }
        return null;
    }
}