I hate shooting black bulls eyes, you cannot see where you are hitting, which will most likely frustrate a newer shooter. At 25yds a 1in target should be visible with irons and at 50 easily with a scope. If it were me I would think about a white 1in circle or square, with a black border for contrast/visibility.
Also, interested in your youtube channel. If you don't feel it appropriate to post please feel free to PM me with a link so I can check it out.
Here is a free one I have been using for a while. Not ideal, the black rings are a little large IMHO, but it get the job done.
