MediaMatters.org is a liberal group so I don't think the "lies" they quote are necessarily correct. There are too many to go into en masse but the first several are opinions of theirs opposing opinions of his and then they call him a liar. That's easy. We could do the same here.
Does Beck go overboard sometimes? Yes! Does he get on a rant and let his mouth take him where his brain should tell him not to go? Yes! But does he come up with a whole bunch of info that no one else is putting out there about this administration and others before it? You betcha, Red Ryder!