Paradox generated 1000 steamkeys that they distributed to youtube let's players and twitch streamers.They gave priority to people who had already been playing/streaming their other very recent title, Cities: Skylines.
The guy from the video above is called arumba. A quick youtube search of "arumba skylines" netted this:
So there is your explanation for why that guy got access.
And honestly, that makes smart business sense.
Only if you are a short term thinker. Long term, disrespecting your early backers in such a fashion is a very sure way to never get such finding again.