I would like to build an image gallery in Flash with AS2 or AS3 that detects automatically the number of images available in a specific folder (say a level below the swf file).
The goal is to don't have to config any xml files with the images to show.
Is this possible?
No. Since Flash is client side technology, this would be a can of worms in terms of security. There are a number ways to enumerate files in a directory using server side technology, wether it be WebDAV or a server side programming language such as PHP. You'd have to decide wether or not any of those may fit your purposes.