In December, the Sanders campaign released an online video (which this post initially identified as a campaign advertisement — see correction at bottom of post) which is particularly interesting. It's basically a standup comedy routine defending Hillary Clinton against a bizarre sexist attack from Donald Trump.

It was released online and then played by television networks in Iowa, which is how it got caught up in the ad tracking. And you can see why it caught the attention of the Iowa media. Come for the Bernie-Sanders-as-Larry-David hilarity, stay for the feminism:

The clip shows a speech Sanders made in Council Bluffs, Iowa, on December 22. Sanders takes down Trump for calling Clinton's extended bathroom break at the previous Democratic debate "disgusting." Clinton was delayed coming back to the debate because the women's restroom was so far away and the lines were so long.

"Donald Trump is very upset. It's very hard for him to deal with — I don't know what his relationship with women has been in his life — but he has discovered that women go to the bathroom," Sanders quips, to guffaws and cheers from the crowd. "And it's been very upsetting for him."

Sanders continues to "admit" that he also went to the bathroom during the debate. "I guess I'm a man, men are allowed to go to the bathroom, but women, what can we say?"

He decries the "pathology" that would make Trump say something like that, and concludes that Trump "must have a very unusual relationship with women."

Sanders has been more aggressive in attacking Clinton in the lead-up to Iowa than he had been for most of his campaign. He's been criticized for dismissing Planned Parenthood as "establishment" for endorsing Clinton, and his campaign has taken heat for some sexist online vitriol coming from its most vocal "Bernie Bro" supporters.

But this clip is a good reminder of Sanders's strong feminist values and his willingness to be vocal about them.

Correction: This post initially said that the clip was an ad the Sanders campaign ran in Iowa, based on it being included in the Political TV Ad Archive, an independent database of campaign ads. But the Sanders campaign clarified that the clip was wrongly tagged as an ad in that database, and that it was in fact a web video they released that was then picked up and played by local TV networks.