For benchmark, I used a dual core computer. Kdenlive profile: ATSC 30fps. Video footage shot in 30fps shows that software decoding is not fast enought to display all frames in real time. Also, there seem to be seek problems, which make the image sometimes garbage. This may not change with a quad-core computer. So I added "unsupported" to avoid any misinterpretation.
If you have a direct URL to some additional footage, please let me know answering this post. Please don't use Rapidshare, rather a direct link to your web space.