He did mention that AC broke records on Twitter and Reddit so Youtube isn't the only aspect. It's specifically his comment on Playstation's metrics being in another league compared to Nintendo's that stuck out to me and made me wonder how predictive these metrics are exactly. I truly don't know how predictive they are.
Well, Mario direct has more viewers than the latest PS5 showcase
and the latest partner direct has 1 million views despite Nintendo already deleted the stream version with ~450k concurrent views for US and ~400k for NintendoJP. If the stream version wasn't deleted perhaps the number is already above 2 million views for mini partner direct
Nintendo has always deleted the streams version of Nintendo direct video with a couple of exceptions like treehouse e3 videos and replaced it with the good quality version right after the stream version ended while Playstation just left it.
Streamed videos = more views inflated by concurrent views during the show and Nintendo deleted that kind of videos.