When I try to download from http://jqueryui.com/download/ I get this page each time: 

Ooops!!!

An unexpected error seems to have occurred. Why not try refreshing your page? Or you can contact us if the problem persists.

I am able to download the same theme in: 1.9.2 (Legacy, for jQuery1.6+). 

I also cannot download any of the gallery themes in 1.10.2 either, so it is not just the custom theme.