The only thing I've found so far is animated GIFs, but they're HUGE.
Please, suggestions and advics requested, as I'm having trouble achieving universality of experience for my users.
Thx.
If the computer viewing the Powerpoint presentation has Quicktime installed, an MP4 (or MOV) can be embedded in the PPT.
Acrobat can also embed MP4 files within a PDF, and seems to use Flash to play it back.
So, using an MP4 h.264 will get you a number of browsers, Flash, PDF files (assuming Acrobat is used to view them - I suspect Foxit and other 3rd-party readers won't do this), with the caveat that the person viewing the file may need to have both Quicktime and Flash installed. OGG and WebM will get you the rest of the browsers (see http://diveintohtml5.org/video.html for more info).