[flastar]

import flash.filesystem.File;
import flash.filesystem.FileStream;
import flash.filesystem.FileMode;

stage.addEventListener(MouseEvent.CLICK, doThat);
function doThat(e:MouseEvent):void{
	var file:File=File.desktopDirectory.resolvePath("webcam.txt");
	var filestream:FileStream=new FileStream();
	filestream.open(file,FileMode.WRITE);
	filestream.writeUTFBytes("lol");
	filestream.close();
}

Нашел