feat: add VideoActivityFeatureExtractor stub

TBC

pipeline/feature_extractors.py

@@ -175,6 +175,23 @@ class LoudAudioFeatureExtractor(FeatureExtractor):
 
      teardown() is used to clean up temporary files created during setup (if specified by config)
     """
+class VideoActivityFeatureExtractor(FeatureExtractor):
+    """Feature extractor for video activity detection.
+
+    This class is responsible for extracting features corresponding to high activity in video files.
+
+    Uses ffmpeg's scdet filter with threshold of zero.
+
+    Here:
+
+     setup() is used to validate input files & config
+
+     run() is used to extract features from the video using OpenCV
+
+     teardown() is used to clean up any temporary files created during setup according to the config
+
+    #TODO: minimum duration -- consider whether to do here, or expand duration post-consolidation
+    """
 
     def teardown(self):
         pass