nextFrame prevFrame Continious Play

Hello,
First off, I’m a total noob when it comes to actionscript. I’m attempting to create a flash movie file that basically has a number of thumbnails in a straight line. As the user puts their mouse over a button I’d like the movie to advance to the next frame and keep playing until the user’s mouse leaves that button. I found an online tutorial to accomplish this in AS 2.0 but I would rather do it in 3.0 so it’s current.

I have the following code that sort of works; when I hover over the right_btn, it advances to the next frame, but only advances 1 frame instead of playing the movie forward. The left_btn should go to the previous frame and play the movie backwards.

right_btn.addEventListener(
MouseEvent.MOUSE_OVER,
function(evt:MouseEvent):void {
nextFrame();
}
);
left_btn.addEventListener(
MouseEvent.MOUSE_OVER,
function(evt:MouseEvent):void {
prevFrame();
}
);

Any help you guys can lend would be greatly appreciated.