Is it right for a server of an open source game to disallow recording?

I've noticed some servers of the open source minecraft clone, minetest, disallows recording for youtube. I find this funny and ethically bewildering not just that the game is released under the LGPL 2.1 but that kids are being told to pull down videos from youtube when its unenforceable.

Remember, you are talking about the server and not the software. The employees of the server company have decided to disallow the recording. It is not funny and ethically bewildering to the owners of the server company.

At the end of the day, it's their site and their rules.

If you don't accept or agree with the rules. DON'T use the site.