I have narrated audio on each of 8 slides using 2013 PP. When emailed to people with (a) 2007 PP running Windows XP or (b) recently downloaded PP Viewer, neither group can hear the audio. I believe it is because I am creating files with .m4p as the extension (true?) and they are unable to read those files. The ultimate goal is to put this PP show on a website that everyone could tap into. Is there an easier way without using YouTube?