With all due respect, you're going about this situation the wrong way. Make the video with womble as best you can, and use that in comparison with the original video to show your grandpa why the video has black bars, and how much video (and detail) he would be missing out on if it were zoomed in.

I would hope that, at that point, he'd understand why the black bars are a necessary evil, and between them and Pan&Scan, the lesser of two evils.

If that didn't work, then I woulnd't waste too much time making such fine adjustments for a preferred P&S version, but that's just my opinion.