My friend got this error when playing in the server with

this mod. Other player work normally

Can you send me his logs?
located in .minecraft/logs/latest.log?

If for some reason he Is not with the PC... You know what Operative System Is using?

I told my friend to send me the log the next time he online. I will post it as soon as I got it.
And he is the only person that is using MacOS with a M2 chip. I don't know if that is the case causing that problem but I will just let you know.

Oh, that's the problem
MacOS requieres manually install VLC (apple Silicon)

Just to know. MacOS Is not supported by WATERMeDIA at all, because Mac Is not for play games. But in your case he only need to install VLC. Enjoy the mod :)