Beamer presentation PDF resolution

[Rich Shepard]

I've used LyX (and LaTeX before this) for a very long time to prepare the
slides (visuals) for presentations. They're always produced in a 4:3
resolution ratio and that's how both xpdf and mupdf display them. This works
fine for in-person presentations projected on a screen by an lcd projector.

However, videos for uploading to YouTube need to be in a 16:9 wide screen
ratio. How can I set the PDF output to a 16:9 ratio using either 1920x1080
or 1280x720 resolution?

TIA,

Rich