Superimpose shapes over video

I’ve searched long and hard to answer this question myself to no avail, yet I’m sure the answer is quite simple and straight forward.

All I’m trying to do is create a "ring" shape on top of a live video stream that can move around freely over the video (somewhat like a target). It seems cv.jit.blobs.centroids actually uses something similar to indicate the individual "blobs" in the video feed, but I don’t know how to replicate this. In fact if you look at the cv.jit.blobs.centroids example, those little circles with the crosses inside them are almost exactly what I want to replicate, except I want to draw them myself and move them around the video feed as I wish.

Any ideas or suggestions?

Thanks!