What exactly do you mean with "from 3d softwares".Do you want to capture something and then create a Screensaver of it or do you want to create your own 3D Screensaver ? I know some programmes of that sort.
http://www.digimindsoft.com/ these are the 3d screensavers i want to make.. How did they manage to make it.. I guess they are all real time 3d. Not captured footage image or avi
Such screensavers are not easy to make.The normal programmes you can get on the net which are cheap can only convert pictures of some other things on models and let them rotate etc.But for creating such screensavers you need other programmes.If you find any programm that can do such things tell it to me i am also interested in that^^.
I would say made in collage between full 3d animation and photography,those on that site are pure 3d realtime videos.They're done in opengl language I woudl say becasue it would take a lot of Ram if you played it as video its special format don't knwo which one.