This is a pretty graphic video.
The poster wonders why they keep on fighting, and I think the answer is simple:
This was filmed in February, which is the mating season for both species. I’d say the male skunk is the primary aggressor, and he’s spent weeks fighting other male skunks in the area. He’s been fighting and mating all month, and he’s just so full of testosterone that he can’t help but attack the opossum, which sort of gives off the vibe of being another male skunk.
The male opossum has been doing much the same, so when he’s attacked, he keeps coming back for more.
Plus neither species is all that smart.
That was pretty gruesome!
And I would have broken the fight by whatever I could do from 200 yards or so away ;-)
I think skunks are probably the least athletic mustelid. A weasel would have made quick work of poor Mr. Possum.
Skunks are mustelids anymore:
https://blogs.scientificamerican.com/tetrapod-zoology/skunks-are-not-weasels/
I think skunks have some qualities which strike me as being covergent with domestication syndrome, because they have that one powerful weapon, it removes a lot of the selection pressure most members of the weasel family are under. They just waddle around eating slugs all day. They remind me of porcupines the way they waddle around seemingly carefree.