Beck DID NOT estimate the crowd size to be over 500 thousand.
Early in the program, he stated that he was happy to report the media had reported over one thousand people had shown up to attend the event. There was resounding laughter, for his lampoon.
Later in the program, he said he had read a report that estimated the attendees to number over 300 thousand and another to that estimated the crowd to number over 500 thousand. He didn’t come up with his own number, and didn’t say that either of these reports were accurate.
He did say at one point that there were an awful lot of people in attendance. (paraphrased) That’s about as close to a solid number as he got from what I watched.
And it was very evident that he was deeply touched at the amazing turnout.