Conservative filmmaker James O'Keefe, who sent ACORN into tailspin last year with an undercover expose but then ran into criminal trouble of his own, has released a new video targeting the Census Bureau.

O'Keefe went undercover as a census worker for two days in which he said he was paid for an extra four hours he didn't work. During the two days before he quit, he says he found supervisors encouraging temporary employees to fill out timesheets for hours they didn't work.

His latest video, released this week at BigGovernment.com, comes as 600,000 temporary census workers fan out in neighborhoods around the country to conduct interviews until mid-July for the decennial national head count, which is the basis for distributing House seats and more than $400 billion in federal aid.

The video also was released less than a week after O'Keefe pleaded guilty to entering federal property under false pretenses, a misdemeanor.

O'Keefe was arrested in January with three others, initially on felony charges of trying to tamper with the phones in a senator's office. The incident was part of a failed attempt to expose Louisiana Sen. Mary Landrieu, a Democrat, for what O'Keefe and his band of activists claimed was her poor record of responding to constituents.

In O'Keefe's new video, he notes that census employees are subject to fines or imprisonment for falsifying the forms. He calculates that if 600,000 Census employees are paid $18.25 per hour and each of them gets paid an extra four hours, it adds up to $43.8 million in waste. He also argues that if 20 percent of their time is wasted on the job, that's more than $1 trillion in waste.

The Census Bureau responded by saying its policies and training clearly "require all employees to honestly submit accurate time records."

"In his video, Mr. O'Keefe, an admitted criminal, does not disclose that he previously worked for the Census Bureau for nearly two months in 2009 without incident, allegation or complaint. That employment with us was well before his indictment and prior to his conviction of a federal crime last week," the bureau said in a written statement.

"The Census Bureau obviously does not condone any falsifying of or tampering with timesheets by its employees," it added. "We are investigating the allegations in Mr. O'Keefe's selectively edited video and will take appropriate administrative action with staff as warranted."

In the undercover video, O'Keefe gets hired as a head counter for the 2010 census and films his training by supervisors in New Jersey.

The 10-minute video shows a census supervisor telling employees to fill out their timesheets each day for eight hours worked – a claim O'Keefe disputes because they were given at least an hour for lunch instead of the 30 minutes marked on the timesheet. And they were told they would get finished well before 4:30 when their shift was supposed to end.

When O'Keefe confronts his supervisor, Vince Fitzpatrick, about the discrepancies on the form, Fitzpatrick tells him it won't be a problem.

O'Keefe then takes his concerns to the regional payroll supervisor, Mary Signorile, who tells him, "Don't be concerned."

"I don't think anybody's going to be questioning it except for you," she said. "So I would just let it go."

But O'Keefe doesn't let it go. Instead, he goes to the top regional supervisor, Edmund Fleckenstein and hands him a letter he wrote requesting to return the money he didn't earn.

"James, quite frankly, we're not often confronted with people that want to insist on giving money back," he said. "So we'll take your letter and we'll forward it to the regional people. Let's see where they take it and what sort of adjustments they make."

But O'Keefe says the bureau has yet to make the adjustments and that the people's tax dollars remains in his checking account.