First of all, it's expensive. Guaranteeing every American a certain sum of money will cost a ridiculous amount.
Second, it's immoral. Taking money from one person and giving it to another by force is wrong, especially when your justification is that you think they have too much money.
Third, it's funny that he points to Social Security when it is approaching disaster. http://www.downsizinggovernment.org/ssa/social-security-reti...
Fourth, the fear mongering about automation needs to stop. Automation will not put everyone out of work and it will not spell the end of capitalism. At every stage of technological advancement, you get people, like the UBIers, who run around like chicken with their heads cut off, Luddite Fallacy. The fact is that automation makes some jobs obsolete but compensates by creating entire industries profitable. Did Software Engineering exist in 1920? No, so don't be surprised if in 20 years a new field has arisen.
I really want to stress the point about automation because I think it is the largest source of misinformation out there. In 1870, 50% of the US labor force worked in agriculture. Today guess how many? 1.2%. Why hasn't the unemployment rate skyrocketed due to the automation in agriculture that allows us to produce more crops cheaper and with less people? Because the increase in labor and decrease in food costs allowed other industries to flourish!