before I type this, note that I am on a mobile device so autocorrect will screw this a bit. Para, you are right that this is grieving and this guy will hopefully be punished. But also, your friend will be punished too because they have an X-ray texture pack. So great job, you reported two people at one time.
Edit: after rewatch8ng the video, I noticed not one block was destroyed, so basically nothing was griefed, whether that matters or not idk, but still I am 100% that your friend is an X-rayer so... yeah.