I have 2 Type-S models and neither rattles like that when hitting the spacebar in any location. If I tap it in just the right spot repeatedly, I can cause it to clink ever so slightly, but nothing like your video. During normal typing, it's as silent as every other key.
In my opinion, if you pay $400 for a keyboard and that price includes a $100 premium for it to be extra quiet, then it should be extra quiet without you having to apply your own mod as a Band-Aid. A little grease, sure. But not o-rings. And if the grease doesn't fix the problem, it should go back for repair. Seriously, it's a $400 keyboard that's built almost entirely of plastic and rubber. It should be perfect.
EK certainly deserves the opportunity to rectify the situation. If it were me, I'd insist on professional repair, despite the long wait time for the round trip to Japan and back.