Ahh got it, I went in the .pack files and saw. Thanks.

No, they edit completely separate files

Any chance this effects the battlefield dust mod as well?

Thank you! I'm glad to know I didn't mess it up. I checked and before the file change my average FPS in a sandstorm battle was 45, and after it was 70.

Mod files and movie files are indistinguishable by your file system. If you open up the file "lessvfxSANDSTORMCHANGETOMOVIE.pack" in your data folder and rpfm says that the packfile is "• Movie" you're done. You won't be able to tell before the game launches because it won't even show in the mod manager, because movie files load when the game loads. Best way to check is to go into custom battle and see.

Using RPFM, I selected this mod file from 3147291877 and used PackFile->Change PackFile Type->Movie to change it to a movie, then I saved as steamapps\common\Total War PHARAOH\data. To make sure the packfile is properly a movie, I went into properties and the type of file still says 'PACK File (.pack)'.

How am I supposed to turn it into a movie from RPFM? The movie option was greyed out before adding the file, and after it was a selectable option, so I thought I did it right. :(

I realised my mistake as I was looking at my two "31" folders and wondering why those are for mods I dolwnloaded mere minutes before disscovering this mod. I didn't have the folder you're talking about because I hadn't downloaded this mod yet. I was reading your instructions thinking this folder was one that existed in vanilla.
I don't have RPFM downloaded but I'll do that since I needed to anyway for other mods.

That was my mistake for not proofreading my description it should be lessvfxSANDSTORMCHANGETOMOVIE.pack in 3147291877

I went to steamapps\workshop\content and I don't have file 3147270840. All the files start with "30" except for two that start with "31" which are both files that only contain the two most recent mods I downloaded.