Try setting boundaries with him, let him know that you are skeptical of his theories and that nothing he can show you will convince you that the corruption is as extensive as he believes. Practice saying NO when he asks you to check something out. Draw a line in the sand. Check out this article with more tips about setting boundaries.
http://www.psychologytoday.com/blog/...feeling-better
As far as Alex Jones goes, nobody takes that guy seriously

he's a classic case of paranoia. Even if Alex Jones did say something true, nobody would believe because it came out of his mouth. As a fellow paranoia sufferer I can sympathize with him but I cannot watch his videos because they trigger my suspicious thought patterns and I start to become delusional again. Word of caution, not all conspiracy theories are false, most of them are misleading. But they usually add nuggets of truth into them to make them more believable.
I definitely believe that this country is under mind control, which is why the term "conspiracy theorist" is so stigmatizing and degrading. People who pointed out that the Mafia existed were once called conspiracy theorists.

Galileo was considered a conspiracy theorist for pointing out that the earth is not the center of the universe. Try to peak his interest into philosophy or some other topic besides conspiracy theories. I found the best way to deal with people like this is to change the subject. People who I don't agree with, I won't talk to about subjects we disagree on because the debate can escalate into an argument, which can escalate into a fight, which can escalate into me being thrown in a jail cell.