The drag and drop works. Thanks!
I've checked the media info of the two files. The HD one has a width of 1280 and the SD one has a width of 720. So, that must be the explanation.
But still, if I watch the SD one using Windows Media Center or Windows Media Player before converting it is shown as wide screen 16:9. How is that done? Is there a way to maintain that aspect ratio, because the 4:3 just seems wrong!
The files are currently being uploaded (check folder "Plantje - Aspect ratio issue" for these). Thanks a lot for all cooperation so far!