No video on this one! I'm still reading Burrows' The Survival Imperative, but I also bought the December issue of The Atlantic for several interesting articles, including one by William Langewiesche that I just finished, "How to Get a Nuclear Bomb" (this link is just a teaser unless you're an Atlantic subscriber, which I'm not any more). The article is an excerpt from an upcoming book, and it is sobering to say the least. The bad news? Plenty, of course, but the big one is that there is a lot of weapons-grade HEU (highly enriched uranium) around, much of it in Russia, and much of it not especially well secured. While getting the necessary ~50 kg needed to make a workshop-built Hiroshima-type bomb would not exactly be a cakewalk, it could probably be done with the help of paid insiders (which is not exactly impossible in Russia).
The good news? "Good" is relative of course, but consider plutonium, which is also pretty common stuff in the world. One "good" point is that plutonium is so hard to work with, that this makes up for the fact that you need so much less of it to make a bomb. Not only is plutonium more toxic and radioactive, making a bomb from it requires precision mechanics and explosives. It's quite hard to do in a garage. Another "good" point is that "ready to use" nuclear weapons are generally held more securely by everyone who has them, and they generally require regular maintenance and special codes to activate them. If someone with the will to use one managed to get one, they would probably use it pretty quickly, while it was still "fresh." So the fact that none has blown up anywhere recently suggests that the bad guys don't have them (yet).
There's other "good" news too, mostly along the lines of "it's harder than you think," but of course there's also more bad news. Perhaps worst of all is the fact that the whole "deterrence" thing breaks down pretty badly when any of the players is not a nation-state. Even a scary/crazy nation-state like North Korea or Iran has a lot to lose if they actually use a nuclear bomb against someone (or even provide one that can be traced back to them to someone else). Leaders may value their own fancy lives even if they don't value the lives of others (including their own people). But parties who lack an identifiable "home field" don't offer any sort of infrastructure to threaten with retaliation. By the way, none of this information is news to anyone (friendly or otherwise) who cares about this stuff. It's all out there.
OK, not too cheery. I say, let's get busy on those space elevators, private space stations, and colonies on the Moon and Mars. We need a backup!