Fix common start video stream

The start video stream method in the common module wasn't using its camera argument, so actually made the argument useful.

common.py

@@ -22,7 +22,7 @@ def display_frame(frame):
 def start_video_stream(camera: int):
     """Starts the video stream and returns the created stream.
     Also waits for the video stream to open before returning it."""
-    video_stream = cv2.VideoCapture(0)
+    video_stream = cv2.VideoCapture(camera)
     return video_stream