il suggerimento di broly mi pare corretto

usando il this._visible o il

_root["container"+k]._visible = false
dovrebbe andare

codice:
function Galleria(path) {
	trace(path);
	//GALLERIA
	for (k=0; k<path[0]; k++) {
		this.createEmptyMovieClip("container"+k, this.getNextHighestDepth()-k);
		_root["container"+k]._visible = false; 		
var mcLoader:MovieClipLoader = new MovieClipLoader();
		var listener:Object = new Object();
		listener.onLoadProgress = function(target:MovieClip, bytesLoaded:Number, bytesTotal:Number):Void  {
			trace(target+".onLoadProgress with "+bytesLoaded+" bytes of "+bytesTotal);
		};
		listener.onLoadInit = function(target:MovieClip):Void  {
			trace(target+".onLoadInit");
		};
		mcLoader.addListener(listener);
		mcLoader.loadClip(path[k+1], "container"+k);
	}
}