VHS and capture: what is the real aspect ratio?
I have tested a 4:3 vhs, and using 5:4 a/r making screenshot report bad final a/r(1:22)
mplayer -aspect 5:4 -vf screenshot

using 4:3 a/r report in screenshot the correct ar(1:31:1)
mplayer -aspect 4:3 -vf screenshot

So I think the correct answer is 4:3.