Slideshow generator can't do padding of videos

I’m preparing a slideshow from photos and videos, and some of the material’s aspect ratio is different than the output video mode.
Some old footage is 4:3 video and I wanted to blur-pad it, but the slideshow generator cannot do it — it works only for photos.
I thought I’d apply the padding to the source material before running the slideshow generator, but it makes it worse: the padding is applied to the source, but then the generator “thinks” the source is still 4:3 and adds black bars on its own.
I hope I described it clearly;)
Am I doing something wrong or it’s just how it is? Any suggestions how to achieve what I want?
Thanks in advance!

(argh, one embedded media in the post only, here’s the outcome of the generator)

I changed this thread to a bug because none of the aspect ratio conversion modes are working for videos. This is fixed for the next release.