fixing mp4 extension

app.py

@@ -502,9 +502,14 @@ with gr.Blocks() as demo:
         "To dig deeper, use the dropdown to filter by file extension and see the bytes added (in TBs) each month for specific file types."
     )
 
+    # get the unique values in the extension column and remove any empty strings
+    extension_choices = [
+        x for x in by_extension_month["extension"].unique().tolist() if x != ""
+    ]
+
     # build a dropdown using the unique values in the extension column
     extension = gr.Dropdown(
-        choices=by_extension["extension"].unique().tolist(),
+        choices=extension_choices,
         multiselect=True,
         label="File Extension",
     )