Setting the wallpaper doesn't seem all that obvious. Initially you look in the Android standard Menu - Wallpaper - Home Screen Wallpaper. Then you can pick a file. This is all fine until you realise that you cannot select the full size of the image. Only a fixed area that doesn't seem to scale.
Instead, I found it easier to resize the image manually to 800x960 and then use the Wallpaper Set and Save App to set the wallpaper.
Converting video for the Samsung Galaxy S is as simple as the ffmpeg command below:
ffmpeg.exe -i %1 -s 800x480 -vcodec mpeg4 -b:v 800k %1.samsung.mp4
Importantly, the screen and resolution on the AMOLED display require a higher than default quality setting on the converted video. Otherwise you'll end up with a poor result.
As with before, paste the above command into a batch file and use it as a command line utility or as a drop target. You will need ffmpeg installed an on the path. But you knew that already right?