Microsoft and Google both offer a feature where the audience can follow along on their device. I've only used the Microsoft version personally... you can watch the slides on your screen, get a translation into the language of your choice, and go backwards in the presentation if you missed something (but not ahead of where the speaker is). If you go backwards and want to get back to where the speaker is, there's a button for that. Seems like the author just needs to RTFM.