The site is called mini dsi tube. It is dsi-compatible even though it was made using webs.com, trust me. If you want to see for yourself keep reading till you get to the link. I must tell you first, sadly, there is no volume. Well, enjoy yourself. http://minidsitube.webs.com/
The requirement of a sister site is that both DSiPaint and your forementioned site are owned by the same person, so no it does not count as a sister site.