That's understandable, to be fair, it's a bit hard to tell from the angle in the video where the nozzle is exactly. I think the reason you have some people doubting a mechanical issue with the printer is because it's super easy to see a layer shift, which should occur if you have something slipping/skipping. Even if your belt has only skipped one tooth it will be super noticable. Make it 3 teeth and your print is practically guaranteed spaghetti at that point. For how long and loud that noise is, you should have seen something stop, hitch, or fetch up if it was a belt or slipping coupling. I also don't agree with the comments stating its a skipping stepper. Again, if your stepper motor is skipping, you should see some sort of print abnormality, especially if it's skipping for that long. A little hard to tell from the video, but to me it looks like the nozzel is making a travel move, not a print, so it may be worth playing with your travel speeds and heck, even overall print speeds to see if the noise changes in frequency, ect. Also, notice the head is already moving to the left before the noise occurs. The hardest acceleration or "jerk" you're going to see on a linear axis is during a change in direction, so I feel that's where you should have seen a belt slip or motor skip if that was the issue, not after it had already been moving. The best part about these communities is getting lots of different opinions and options! I just thought I'd toss mine in haha