It's 100% normal. I wanted to post a response to this video question for the next guy who's wondering if his KTM 500 sounds normal. I found this post in a google search. Yes, that amount of noise is 100% normal. I work with KTM's for a living, I've worked on 100's of them. Some 500's are louder than others, but they all have a tick that sounds like valvetrain and most have a knock that sounds like something in the bottom end. The bike in the video is one of the more knock-ish sounding engines, but it's fine. There is a rattle that comes and goes by pulling in the clutch which is often worn inner hub dampers, but even when they're new you'll be able to change the sound by pulling the clutch lever.
I hope this thread, the OP's video, and my response help someone in the future.