There's a short (22-minute) documentary on Sergey Karjakin entitled "Sergey: At the Epicenter of Chess and Politics". It does a nice job of dividing his career into stages, thereby offering an implicit answer to two questions: why did it take him so long to go from being the youngest grandmaster ever to a serious candidate for the world championship, and why did he move from Ukraine to Russia in 2009? It's a bit less successful, it seems, in explaining why he has adopted such a strongly pro-Putin outlook in recent years, though one can easily grasp his general embrace of Russia. At any rate, it makes for good viewing, and is in my view worth a couple of dollars to watch once or about four dollars to buy. (Both for the work in its own right, and to encourage filmmakers like Alexander Turpin to make more such films in the future.)