I don't get it, why .png the website says you need svg for better drawing videos. Can you get the svg files?
Just tried some of the png files in videoscribe and they s*ck it draws faint barley visible lines until it finishes then the image appears. Need the .svg files for this to be any good. If you have access to this site hopefully you can get the svg files.
PNG file cannot draw well in Sparkol, if you really want the best quality drawing image in Sparkol, you need SVG file.. you can convert those PNG files in InkScrape or Adobe Illustrator.