That didn't happen in Legion or BFA so it won't happen this time either. It's a global release mate, no one has access to the cinematics other than Blizzard until they get triggered in game for the first time.
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Also helped that we weren't in the same zones. Not only were Alliance/Horde on seperate continents but also you could pick any of the 3 zones of that continent. We also didn't worry about a scenario intro because we've all already done it due to early access weeks before the release. Shadowlands is opening with the Maw, followed by everyone being in Bastion and following the same linear zone order after that. We haven't had a launch like this since MoP with everyone being in Jade Forest. I'd be very surprised if the launch was as smooth as Legion or BFA were, but I do imagine they'll be putting Classic's layering tech to use so it won't be another WoD launch.
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All cutscenes have already been available on the beta, just with a red cross over them saying WIP. Oribos thing is a cinematic that is yet to be seen, not a cutscene, the interview did some poor wording if they actually wrote cutscene.