I saw that, I was looking for the quote where he called voters sexist, not one where he noted there was latent sexism involved in how Clinton has been treated compared to Trump. Any professional woman knows that the latter is true, it's no great revelation.
Obama is asked what he believes the equivalent to birtherism will be to Hillary Clinton. If you recall, it birtherism was not some kind of across the board prospect for all people against Obama, but a subset of them who decided for some reason that Obama wasn't born in this country, something I doubt they'd do if he were Jim Smith of Hawaii. For Hillary, he thinks it will be attacking her as a woman as opposed to not being in the country.
Though I'm sure you'll find the facts less compelling than the myth.