Update README.md

README.md

@@ -80,7 +80,7 @@ The videos:
 
 The annotations in `dataset`:
 - `sample_key` a unique key.
-- `videos` metadata about the videos A and B used by the dataloader.
+- `videos` metadata about the videos A and B used by the dataloader: the video filename, and the start and end frames.
 - `action` action key like "fitness_2"
 - `action_name` a short action name, like "deadlift"
 - `action_description` a longer action description, like "a single free weight deadlift without any weight"