I'd have thought that would have already been clear in the licencing contract.
"The material is licenced to the purchaser for the purposes stated in appendix A. Ownership and copyright of the material remains at all times with the seller".
So a copyright claim by Epic/Sony would be breach of contract, and hopefully there would be a clause in the contract that the licence is immediately cancelled should there be such a breach of contract.
At least, that's how I would licence any material of mine.
Sony has obviously sent a copy of the video to their legal/enforcement division (did they have a licence to copy the material for that purpose?), who proceeded to scour youtube/vimeo/liveleak for it, without bothering to check who *actually* held the copyright in the original footage.