From what I can tell (not trialed) you can actually be near your muster deck in advance (no stairs), once called, get card scanned, wait until elevators work (ie, grab a drink), then once back in cabin, watch video and call that number. I only say this because we watched the video, followed directions and got a letter which said we didn’t watch the video. Rewatched the video, dialed in the # and all good.