You could try converting them with Freemake video converter, although they put a logo at the beginning and end of the resulting video as well as a watermark in the top right corner. I just did a quick test with that file and seems to me it did the trick. You just need to convert using custom settings rather than one of the presets but I downloaded from youTube as mp4, chose convert to mp4, then choose "Custom" from the drop down list, then click on the "edit preset" blue button. The last box in the frame size row is Adjustment. Click on that and it gives you choices for stretching or adding black bars etc. I just chose "Auto" and it did a pretty good job I think but you can play around with it to get just what you want.
(If one only wants to see the video, not burn as DVD movie, then vlc media player is perfect.)
