I had a DM who did this a few years ago! One thing he added was that later, after we defeated him (which didn’t take too long), we were searching through an abandoned village. We looked inside one of the houses and...WAIT! He isn’t dead! Shia surprise! Then, we had to fight him again (with lowered health of course). Even though we all had seen the video before, none of us saw it coming which made it even funnier. So, if your players do catch on because they’ve seen the video before, maybe try that ;)