well its hard to see, but I think I cought a glimps of the males claspers around the 52sec mark of the video. Thats one good way to tell if he is even ready to have fun like that with the female.
To me, looks like its a breeding thing. Like the others, cant say for sure, but thats what it looks like to me.
If you can, get a close up shot of the male around were the tail meets the body..
that way we can tell if he is mature enough even to breed. Second, how old are the rays??...
Rays like to play, but usually in my exp dont do that kind of damage unless he is trying to mate her.. But I could be wrong.. I myself have not had mine long enough and my males are not mature enough yet to mate..
If there is improvement in her healing when they are seperated, then I would say he is the cause of it.. Not alot you can do if it is him, either let them mate, when she gets knocked up he will leave her alone for awhile, or just have to seperate forever.. lol
hope this helps