If I remember correctly that guy gave those estimates a while back, before AMD and NVidia revealed their 480 and 1060 GPUs which have greatly reduced the cost of building or buying a VR Ready PC.
And there must be over 400,000 HMDs in homes right now, so even if he said this yesterday he's only expecting 100,000 to be sold between now and New Year's Eve. You'll probably see
at least the same amount of HMDs sold again that have been sold between the day that pre-orders opened and today before the end of year considering that the time period includes the Christmas shopping season.
We'll have to wait and see, but my 1m guesstimate is going to be closer than his. Only 100,000 sold between now and the end of the year..? Good luck with that lol
Edit: Yup, that guy made these predictions on 6th March, before either HMD had launched. The sales of both the HTC Vive and Oculus Rift have surprised
everyone so far, including HTC and Oculus themselves.
We don't know how many Rifts have been sold so far but now that I've done a quick search on Google, going by SteamSpy figures you'll be looking at around 100,000 Vives sold so far (can't remember where I got 120,000 from now).
Even if Oculus have only sold 250,000 and HTC have sold 100,000 that's still 350,000, more than the lowest estimate he gave for 6th March 2016 - 6th March 2017. Even his highest guesstimate
for the year would mean that both HTC and Oculus would only sell, what..? 150,000 units, between them, between now and 6th March 2017.