Use the depth to indicate which layer a particular root clip is, and then use that to calculate it's `_leveln` path.

core/src/avm1.rs

@@ -951,6 +951,7 @@ impl<'gc> Avm1<'gc> {
                 MovieClip::new(NEWEST_PLAYER_VERSION, context.gc_context).into();
 
             layer.post_instantiation(context.gc_context, layer, self.prototypes.movie_clip);
+            layer.set_depth(context.gc_context, level_id as i32);
             context.layers.insert(level_id, layer);
 
             layer

core/src/avm1/script_object.rs

@@ -588,6 +588,7 @@ mod tests {
             let swf = Arc::new(SwfMovie::empty(swf_version));
             let mut root: DisplayObject<'_> = MovieClip::new(swf_version, gc_context).into();
             root.post_instantiation(gc_context, root, avm.prototypes().movie_clip);
+            root.set_depth(gc_context, 0);
             let mut layers = BTreeMap::new();
             layers.insert(0, root);
 

core/src/avm1/test_utils.rs

@@ -27,6 +27,7 @@ where
         let swf = Arc::new(SwfMovie::empty(swf_version));
         let mut root: DisplayObject<'_> = MovieClip::new(swf_version, gc_context).into();
         root.post_instantiation(gc_context, root, avm.prototypes().movie_clip);
+        root.set_depth(gc_context, 0);
         let mut layers = BTreeMap::new();
         layers.insert(0, root);
 

core/src/display_object.rs

@@ -581,8 +581,7 @@ pub trait TDisplayObject<'gc>: 'gc + Collect + Debug + Into<DisplayObject<'gc>>
             path.push_str(&*self.name());
             path
         } else {
-            // TODO: Get the actual level # from somewhere.
-            "_level0".to_string()
+            format!("_level{}", self.depth())
         }
     }
 

core/src/player.rs

@@ -235,6 +235,7 @@ impl Player {
 
             for (_i, layer) in root_data.layers.iter_mut() {
                 layer.post_instantiation(gc_context, *layer, mc_proto);
+                layer.set_depth(gc_context, 0);
             }
         });