So, instead of discussing the topics in the video, the majority of commenters here are discussing the flaws of the website it's hosted on or debating whether or not reddit is profitable. Neither of which has ANYTHING to do with scaling.
I expected better, people. Seriously.
In this and some other technical topics, people end up discussing their personal tastes with web site's design, their individual UI frustrations with some button on the web site, the font, the color, and other random non-relevant topic; like now the profitability.