Issue: mobile scroll is not working over the image but scroll is working in empty space or below the image.
You will see the issue also on your demo like http://casual.demo.ubertheme.com/nulla-ullamcorper.html
HOpe of your helping.
I know the solution please share the FTP i will help you fix this.
I fixed it and changed the file: /app/design/frontend/default/dasgibtesnureinmal/template/catalog/product/view/media.phtml
Please let me know if you need help further.