Yes, he told us on his radio show too...(this would be the context to the edited version of the interview in Forbes):
Glenn Beck - Current Events & Politics - You're Being Set Up, America
If you've been a long time viewer of this show and listener of my radio show, then you remember a time when the show was based in comedy. We looked at the news of the day and tried to get a point across in the funniest way possible. Today is a different story. The show is now about as funny as smallpox.
Recently, I got all kinds of heat for telling Forbes magazine that my company is an entertainment company. But they only printed half the quote. The rest of the quote was about how I very much believe the republic is on fire, I just don't think the best way to solve it is with a cartoon dog carrying a fire hose....
Glenn always says he "doesn't give a flying crap" about things. His show isn't focused on politics like Hannity's show. It's about the principles that made this country great. His 8/28 rally isn't about politics, the 8/27 meeting the night before is about bringing all the religions together as one to help our country (he personally wrote the check to rent the Kennedy Center for that night...again, not political) and the 9/12 movement which started it all has nothing to do with politics.
His show is entertainment and serious stuff, although it's mostly serious nowadays. But yes, they are an entertainment company as well as (the part Forbes left out) a group of people who are concerned about the direction of our country.