I would recommend "smart deinterlace (2.8 beta)" from Donald Graft. Much better the the deinterlace filters virtual dub has on board. Search for it in a search engine, download the zip file and unpack it in the plugins folder then add it in the vd filter menu.
I have used this filter in the past for rendering before I developed my own avi-synth scipts wich are secret like the coca-cola mixture
