Do you mean like storing a list of the swf files, then when a user clicks next it jumps to the next swf file in the list and back goes back one in the list? If so you can do that using an array.. I was about to explain how, but hey it would be easier for me to just code something up for you! Check it out below, I've tried to comment it enough so you can figure out how it works. 
PHP Code:
//your swf list can be anything and any length. I named them one two three so you can easily test that it works
var swfList:Array = new Array("one.swf", "two.swf", "three.swf", "four.swf");
var i:Number = -1;
//where next button has an instance name of 'nextBtn'
nextBtn.onRelease = function(){
i++;
if(i > swfList.length - 1){
i = 0;
}
trace(swfList[i]);
//your load funtion here like loadMovieNum(swfList[i], 1); or instance name.loadMovie(swfList[i]);
}
//where previous button has an instance name of 'prevBtn'
prevBtn.onRelease = function(){
i--;
if(i < 0 ){
i = swfList.length - 1;
}
trace(swfList[i]);
//your load funtion here like loadMovieNum(swfList[i], 1); or instance name.loadMovie(swfList[i]);
}
enjoy! and welcome to FK