There is really no such thing as 4:3 or 16:9 on tape. SD tape is SD tape, it is always 720×480 then the monitor much match the aspect ratio of those pixels to the way that it was shoot.
16:9 displays correctly at 1.2 and 4:3 at .9.
As long as you keep things the same all the way through the editing process you are good. The problem is there is nothing you can do (short of letterboxing) that will make a 16:9 sequence recorded to tape play-out to a 4:3 TV and not squash it. Either the TV needs to have a 16:9 mode or you have to letterbox the footage.
A 16:9 DVD looks correctly because the play is in fact letterboxing the video on the fly.