Код:
this.createEmptyMovieClip ("mcMaska", 1);
this.createEmptyMovieClip ("mcImage", 0);
var mc = this.mcImage.createEmptyMovieClip ("mcImage", 0);
this.mcMaska.lineStyle (0, 0);
this.mcMaska.beginFill (0);
this.mcMaska.lineTo (100, 0);
this.mcMaska.lineTo (100, 100);
this.mcMaska.lineTo (0, 100);
this.mcMaska.lineTo (0, 0);
this.mcMaska.endFill ();
this.mcImage.setMask (this.mcMaska);
mc.loadMovie ("big.gif");