I guess I should have looked more into what a Wilhelm Scream is. As I was posting my question, I was in the middle of researching public domain footage for a project I was working on. I saw your post and just plugged in “Wilhelm Scream” into the search for kicks to see what came up, and that was the link.
Everything on that site is public domain, including footage, audio files, and much more. If it’s on that site, it’s public domain. My mistake for not doing a bit more research into what a WIlhelm Scream is, sorry 🙂
cheers