Members of Massachusetts Sen. Scott Brown's (R-MA) staff were seen on a video posted on YouTube Tuesday where Brown's supporters did a sports chant, presumably mocking senatorial challenger Elizabeth Warren's Native American heritage.

WCVB-TV confirmed that Brown's Deputy Chief of Staff Greg Casey and Constituent Service Counsel Jack Richard can be seen in the video, as well as a state Republican operative, Brad Garrett.

The video, posted by "BlueMassGroup," takes place at a rally for Brown, and shows a group of his supporters shouting "war whoops" and doing the "Tomahawk Chop" chant popularized by Atlanta Braves fans in the 1990s, and chanting "Yankees Suck," referring to the New York Yankees.

"It is certainly something that I don't condone," Brown told the station. "The real offense is that (Warren) said she was white and then checked the box saying she is Native American, and then she changed her profile in the law directory once she made her tenure."

Brown's statement underscores his recent tactic of attacking Warren on the issue of her heritage. A new Brown campaign ad is composed of news clips questioning Warren's claims that her mother was part Cherokee and part Delaware Indian, which critics say she exploited for professional gain.

Warren responded with an ad explaining that her mother and father eloped because of disapproval on the part of her father's family.

"I never asked for and never got any benefit because of my heritage," Warren says in her ad. "The people who hired me have all said they didn't even know about it."

Politico Executive Editor Jim Vanderhei said on MSNBC Tuesday morning that Brown's attacks are a response to an increase in Warren's popularity following her appearance at the Democratic National Convention earlier this month.

"Scott Brown -- who has pretty good favorability ratings in the state, but he's running in a very Democratic state -- knows that he's down right now," VanderHei said. "He has to do something to rattle Warren. He has to do something to shake up this race, and so he went after her hard on that."

Watch the video from the Brown rally, posted on YouTube Tuesday, below.