Ultimately (and not long from now if these rates of adjustment continue), mining will be a commodity business with a very small profit margin. When you consider that there are uses for low grade heat (like home and office heating), once the ASICs catch up with Moore's law, it seems likely that the profitability will be slightly negative for someone trying to run this kind of business. (As another reason, there will probably be people who have access to basically free electricity that would have been wasted, and just need to amortize the cost of the ASICS).
However, because mining is a zero sum game, we can conclude that the profitability of mining was very high at the time of the making of this video, or else the margins wouldn't have been able to drop as much as they did. This says that a rational large investor would choose to put their money into mining rather than directly buying bitcoins, if they were interested in getting into this space. That's probably why the price has been falling since the peak early last year.