Cf my response to other commenters who raised a point similar to yours. Of course I'm not expecting the talk to be thoroughly vetted 6 months in advance. Howeve

Cf my response to other commenters who raised a point similar to yours. Of course I'm not expecting the talk to be thoroughly vetted 6 months in advance. However, demanding that all speakers give their talk internally a month or two in advance, if only for the sake of technical correctness/typos/etc., seems like a very reasonable minimum.