Director Barry Levinson’s 90-minute “Poliwood” is billed as a film essay.

That’s like calling the back of a cereal box a novel.

Say what you will about Michael Moore, but at least he knows how to spin a story.

Levinson (“Rain Man”) aims to explore the crash of politics, celebrity and media. He’s fascinated as to why performers are greeted with hostility when they become politically active.

He trails famous members of the Creative Coalition, Hollywood’s nonprofit, nonpartisan lobbying group for arts funding, through the 2008 Democratic and Republican presidential conventions.

The coalition’s trip to the Obama convention is practically a party, drawing Anne Hathaway, Susan Sarandon, Ellen Burstyn and Spike Lee, among others.

As “Poliwood” demonstrates, movie and TV stars have unprecedented access to DC’s elite. A pair of congressmen are only too happy to answer Sarandon’s questions about Fannie Mae’s collapse. Tim Daly (who also served as co-producer here) banters with a politician who wants a movie career.

But when a communications specialist reminds the lefty celebs that they must tone down the vitriol when addressing Republicans, stars such as Josh Lucas and Gloria Rueben react as if he spat on their designer shoes.

Thin-skinned, these superstars.

As you might expect, the wattage dims for the Republican convention. Suddenly all these nonpartisan activists are busy. Coalition co-founder and actor Ron Silver, looking wan (he died from cancer in March), speaks about the left’s intolerance. Levinson appears to shut down.

A handful of performers, including Daly and Rachael Leigh Cook, meet with average voters. The stars are unprepared for the fury directed at them by working folks sick of the elite telling them how to vote.

Levinson’s most trenchant observations come as he covers the pageantry of the two conventions and notes how every event is orchestrated to play to the network cameras.

“So, being telegenic is important to being president of the United States,” Levinson says. “Where would that leave Lincoln? That’s not a telegenic face.”

Levinson declares TV to be the single most addictive, destructive force in society today, destroying families and our democracy. (There’s no mention of that little thing known as the Internet, which played such a large part in the election.)

Late in the film, MSNBC’s Tucker Carlson seems to settle the question of whether celebrities have a right to become politically involved. He argues that most people should own their ignorance.