http://www.bezzmedia.com/swfspot/tutorials/flash8/True_Fullscreen_Flash_Mode

En la documentación oficial de Adobe se encuentra el siguiente texto:
“The Stage object is not globally accessible. You need to access it through the stage property of a DisplayObject instance.”

Así que para que la linea

stage.displayState = StageDisplayState.NORMAL

funcione, deberá ser invocador por una clase que extienda de DisplayObject. De no ser así, obtener el stage a través de algún DisplayObject que esté disponible.

Ejemplo:
myMovieclip.stage.displayState = StageDisplayState.NORMAL

No olvidar que la propiedad stage empieza a ser válida una vez que el DisplayObject ya fue agregado en la escena (osea, luego del evento Event.ADDED_TO_STAGE )

var myMovieclip:MovieClip = new MovieClip();
trace( myMovieclip.stage ) // null

FLASH CS4:

Reproductor: Flash Player 9 [ * Versión del player no del SOFTWARE]
Script: ActionScript 1.0

Código de mi clip de película:
on(release){
if(Stage.displayState == “normal”){
Stage.displayState = “fullscreen”;
}else{
Stage.displayState = “normal”;
}
}

[ * Cuidado con los mensajes de error al momento de compilar, es posible que te avise de las comillas, y cambiarlas a comillas rectas. Esto era lo que impedia que se ejecutara mi código correctamente, pues copie el código de arriba y lo pegé]

HTML:

Usando el Dreamweaver CS4 seleccioné el objeto, voy a Parámetros, click al botón “+” y agrego: Parámetro: allowFullScreen Value: true

Listo, tienes el fullscreen funcionando.
Si alguien desea ayuda le dejo mi email, orphe@live.com

Saludos
Roberti

Estas son las funciones que intervienen en dicha tarea:

function setFullScreen(e){
if(p.used_in_other_flash_file==false){
p.W = stage.stageWidth;
p.H = stage.stageHeight;
}
if(stage.displayState == “fullScreen”){
stage.displayState = “normal”;
p.bg.width = p.W;
p.bg.height = p.H;
p.bg.alpha = 1;
} else {
p.bg.alpha = 1;
stage.displayState = “fullScreen”;
p.bg.width = p.W;
p.bg.height = p.H;
}

p.resizeVideo();
setToolbar(p.bg.width – 20);

p.gallery.x = p.bg.width/2 – p.gallery_width/2;
p.gallery.y = p.bg.height/2 – p.gallery.height/2;

p.big_play_btn.x = p.bg.width/2 – p.big_play_btn.width/2;
p.big_play_btn.y = p.bg.height/2 – p.big_play_btn.height/2;
if(p.contains(p.single_image_holder))p.setSingleImagePosition(p.single_image_holder);
p.video_mask.width = p.bg.width;
p.video_mask.height = p.bg.height;
}

function resizeEvent(e){
if(p.used_in_other_flash_file==false){
p.W = stage.stageWidth;
p.H = stage.stageHeight;
}
p.bg.width = p.W;
p.bg.height = p.H;
p.video_mask.width = p.bg.width;
p.video_mask.height = p.bg.height;
p.bg.alpha = 1;
p.resizeVideo();
setToolbar(p.bg.width – 20);

p.gallery.x = p.bg.width/2 – p.gallery_width/2;
p.gallery.y = p.bg.height/2 – p.gallery.height/2;

p.big_play_btn.x = p.bg.width/2 – p.big_play_btn.width/2;
p.big_play_btn.y = p.bg.height/2 – p.big_play_btn.height/2;

if(p.contains(p.single_image_holder))p.setSingleImagePosition(p.single_image_holder);
}

function setToolbar(w){
if(w>600)w=600;
var btn_gallery_space = 6;
if(btn_gallery.width == 0) btn_gallery_space = 0;
btn_reset.x = btn_pause.x = btn_play.x = 6;
seek_bar_width = w – 6 – btn_reset.width – 6 – 6 – timer_bg.width – 6 – btn_volume.width – 6 – btn_full_screen.width – 6 – btn_gallery.width – btn_gallery_space;
bar_progress.x = bar_loaded.x = seek_bar.x = btn_pause.x + btn_pause.width + 6;
bar_progress.setWidth(seek_bar_width);
bar_loaded.setWidth(seek_bar_width);
seek_bar.setWidth(seek_bar_width);
timer_bg.x = seek_bar.x + seek_bar.width + 6;
player_timer.x = timer_bg.x;
btn_volume.x = timer_bg.x + timer_bg.width + 6;
btn_full_screen.x = btn_volume.x + btn_volume.width + 6;
btn_resize.x = btn_full_screen.x;
btn_gallery.x = btn_full_screen.x + btn_full_screen.width + 6;
bg.drawRectangle(w, 24, 5);

if(p.used_in_other_flash_file == true){
btn_full_screen.visible = false;
btn_resize.bg.visible = false;
btn_resize.y = btn_full_screen.y;
btn_resize.visible = true;
}

x = p.bg.x + p.bg.width/2 – w/2;
y = p.bg.height – 30;

buffer_preloader.x = bg.x + bg.width/2;
buffer_preloader.y = bg.y – 12 ;
}
function resizeVideo(){
_video.width = _video.videoWidth;
_video.height = _video.videoHeight;
////
var sx:Number = 1;
var sy:Number = 1;

if(bg.width != _video.width)sx = bg.width/_video.width;
_video.width = bg.width;
_video.height = _video.height * sx;
if(resizeMode == “fitScreen”){
if(_video.width > bg.width){
sx = bg.width/_video.width;
_video.width = bg.width;
_video.height = _video.height * sx;
}
if(_video.height > bg.height){
sy = bg.height/_video.height;
_video.height = bg.height;
_video.width = _video.width * sy;
}
} else {
if(_video.height < bg.height){
sy = bg.height/_video.height;
_video.height = bg.height;
_video.width = _video.width * sy;
}
}

console.appendText("sx = " + sx.toString()+ " " + " sy= "+ sy.toString() + " video : "+ _video.width );

_video.x = bg.width/2 – _video.width/2;
_video.y = bg.height/2 – _video.height/2;
video_mask.width = bg.width;
video_mask.height = bg.height;
}