Would you be more likely to present old (published) work than the latest (unpublished) results and ideas?
- Would you work harder to ensure that any images you project are either entirely of your own construction or, if borrowed from another source, properly credited?
- Would you spin your talk in a different way, in recognition of a possibly wider audience beyond those present during the initial recording?
- Would you do anything different about your dress, mannerisms, voice, piercings etc. knowing that you are being recorded vs. just speaking to those you can see sitting rapt in their seats in front of you?
Maybe that makes for a better, more focused talk. Maybe that makes for a more boring talk. I don't know, but although recording and distributing talks has many positive consequences, recording a talk and making it available for a wider audience is not a neutral activity and would certainly have some impact on talk content and perhaps also style.