In the video it sounds like metal on metal play due to tolerance gaps inside the clasp. Don't own a Rolex so not sure how normal that is for that watch.
I just performed a similar test on my X-33 titanium bracelet. If the bracelet is on the skinniest part of my wrist and has a decent amount of slack (sized for summer and sports) then I can hear a clicking sound when I tap it at the Omega long end. A bit quieter but that may be due to the titanium versus steel. I can see it's clearly coming from the clasp (logo side) tapping against the connecting link underneath. This seems normal to me given the amount of bracelet slack. If I move the bracelet to a thicker pat of my wrist right near my hand then the sound goes away since the light tapping isn't enough to push the clasp into the link.
Unlike the video where the sound seems to be metal on metal collision inside the clasp, mine is clasp to link (perfectly normal). I guess you'll have to see if yours is internal or external to the clasp. Observe to see if the sound is being caused by the clasp end hitting the link underneath. Best check is to make sure there is little to no slack on the bracelet when you tap the clasp.
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