need help with tracking a tennis ball in a video

[gqdeep01]

I have this python code, but it seems to be tracking something off to the side of the video. the code is supposed to draw a red circle around the ball so i know it can see it. but the red circle is off to the right, and only showing a little bit of it, please let me know what i need to fix. thanks

[wabbity]

Maybe not just draw the largest circle, try drawing them all?


EDIT:
maybe do your speed calcs before drawing the ball and only draw positive speed items?