[Kikasso]

или при аттаче:

function a70(){ this._alpha=70;  }
function a100() { this._alpha=100; }

attachMovie ("clip", "clip1", 1, {onRollOver:a70, onRollOut:a100, _x:10 } );
attachMovie ("clip", "clip2", 2, {onRollOver:a70, onRollOut:a100, _x:20 } );
attachMovie ("clip", "clip3", 3, {onRollOver:a70, onRollOut:a100, _x:30 } );

Или задействовать watch:

function alphaMan( prop, oldval, newval ){
if(oldval) oldval._alpha = 100;
if(newval) newval._alpha = 70;
return newval;
}

var hilited:MovieClip;
this.watch("hilited", alphaMan );

function a70(){ hilited = this;  }
function a100() { hilited = null; }

attachMovie ("clip", "clip1", 1, {onRollOver:a70, onRollOut:a100, _y:100, _x:100 } );
attachMovie ("clip", "clip2", 2, {onRollOver:a70, onRollOut:a100, _y:100, _x:200 } );
attachMovie ("clip", "clip3", 3, {onRollOver:a70, onRollOut:a100, _y:100, _x:300 } );