How can i export my video as de-interlaced footage??? 
I think, unless you rendered with ‘Fields’ enabled it should be de-interlaced by default.
Are you rendering for television?
EDIT - Found this - http://blenderartists.org/forum/showthread.php?p=1144302
thanx organic, i m not rendering for tv, but for vimeo and they reccomend to export as deinterlaced as well as another video sharing sites; the problem i m facing is the flickering at the begining of thisanimation, at the very begining first, and then once you have got into the monitor. Any idea how to solve it? i think it is due to interlaced video but i m not sure now. thanx in advance
Is it very subtle? I don’t see any flickering.
Did you composite the video in the link in blender?
Did you use interlaced video source material, if so consider deinterlacing to an image sequence before bringing into blender for the comp. AVIsynth works well for this.
It looks like it has been resized to a larger dimension. The addition of compression artifacts also may be degrading quality. (Hi pablow!)