Doesn't he manually change the blizzard bar textures though, and not default ones? I'm not adept on .lua coding but I did play around a bit with some stuff including LUF. A theory of mine would be to:
1. Implement these textures manually (as in not in the addons folder, but interface folder). Since they should be overriding the Blizzard bar textures.
2. Then using Blizzard bar if that's a texture option in LUF. If it's not an option, you could find an addon that does include the default blizz bar in it's textures, then copy over that and import it into LunaUnitFrames\media\textures, and overwrite it with a name of one of the existing textures in that addon. One that you don't use.
3. Test it out and apply that blizzard bar while in game with /luf menu.
Something to note. SantaUI overwrites default blizzard textures and frames through Interface, and is not technically an addon. It is also dated for WotLK afaik. So if you have issues, the author of LazyPig made a similar one:
https://github.com/satan666/UI-TEXTURE-PACKSeems very similar so perhaps he just backwards engineered it or straight out took it. I for one know the github one works (or did when I tested a week or so ago). However, how it will work with my theory on applying such textures with LUF is something I do not know the outcome of. So backup ur Interface, WTF and Font folders if you have such, as you could potentially end up with bugs you don't want.
Another possible solution is that I send you a texture pack I found laying around in certain UI packs. It's very similar to ElvUI/TukUI (the originals, never tested the one for vanilla). I already put it in my edit of LUF's nice addon, was eventually gonna make my own UI pack to upload here but someone pointed out there are enough similar UI packs here so was just gonna use it for personal use x) But if none of the above works I could pm you my thing (sounds dirty aw ye) and you can see if it's the texture you want or not.