Yeah.. I have 1GB GTX550TI and quite shitty FX-4100. I have to play minium settings (normal) but 1080p. When I'm ready with the editor I put settings as high as I can (1080p high-ultra, GPU memory goes over 2,5gb in settings / 1gb 550TI) = Game is now running 10-20fps, but video editor renders the video at 60fps
Of course there is sometimes artifacts, bugs etc because 550 TI simply can't handle GTA V good enough, but yeah.
I'm buying new (used) GPU too soon, and some day also CPU. This is pretty shitty PC I have now..