[Bug] Fix Kinetics format to have media (openvinotoolkit#1223)

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### Summary

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Resolves openvinotoolkit#111 and openvinotoolkit#222.
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CHANGELOG.md

@@ -33,6 +33,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   (<https://github.com/openvinotoolkit/datumaro/pull/1220>)
 - Fix broken link to supported formats in readme
   (<https://github.com/openvinotoolkit/datumaro/pull/1221>)
+- Fix Kinetics data format to have media data
+  (<https://github.com/openvinotoolkit/datumaro/pull/1223>)
 
 ## 16/11/2023 - Release 1.5.1
 ### Enhancements

src/datumaro/plugins/data_formats/kinetics.py

@@ -65,11 +65,13 @@ def _media_files(self, subset):
             return self._subset_media_files[subset]
 
         subset_path = self._subset_path(subset)
-        self._subset_media_files[subset] = {
-            osp.splitext(osp.basename(f))[0]: osp.join(subset_path, f)
-            for f in os.listdir(subset_path)
-            if osp.splitext(osp.basename(f))[1] in VIDEO_EXTENSIONS
-        }
+
+        self._subset_media_files[subset] = {}
+        for root, _, files in os.walk(subset_path):
+            for f in files:
+                key, file_extension = osp.splitext(f)
+                if file_extension.lstrip(".") in VIDEO_EXTENSIONS:
+                    self._subset_media_files[subset][key] = osp.join(root, f)
 
         return self._subset_media_files[subset]