Update comments

pytube/utils.py

@@ -28,6 +28,14 @@ def safe_filename(text, max_length=200):
 
 
 def print_status(progress, file_size):
+    """
+    This function - when passed as `on_progress` to `Video.download` - prints
+    out the current download progress.
+
+    Arguments:
+    progress -- The lenght of the currently downloaded bytes.
+    file_size -- The total size of the video.
+    """
     percent = progress * 100. / file_size
     status = r"%10d  [%3.2f%%]" % (progress, percent)
     status = status + chr(8) * (len(status) + 1)