the ground plane and the dome used in the video are downloadable ... in the attachments section
on the web there's special panoramic images which can be used to light 3d scenes and can serve as backdrops -
they are sometimes called "spherical" sometomes "equirectangular"
there's a nice collection of them at sIBL ( http://www.hdrlabs.com/sibl/archive.html )
Also see : https://sites.google.com/site/mcasualsdazscripts4/mcjsphericaluv
Also see : https://sites.google.com/site/mcasualsdazscripts5/mcjskysphere
Note: the sphere and ground plane used in the video titled "3d environment sphere + plane"
are ground_XZ_100ft_Y150cm.zip and ball_D_100ft_Y150cm.zip
also note that a slightly better version of that dome will probably be posted soon
and also note that the script that was used to generate them will be posted soonishingly