New, slightly simplified version that seems to work pretty good on both Mac and PC. Download it here:

goodmotion.se/GM_FoldLayers_1.0.1.zip

The plugin was created by Petter Bergmar, twitter.com/@pbergmar

The video should explain what it does, for some people a great way of uncluttering your timeline while others prefer standard "shy" switching or something more advanced like aescripts.com/zorro-the-layer-tagger/