How to upload video and grab image in windows platform

I am working on Video Library project.It is running on windows
platform.I have installed r-image and ffmpeg. Right now I am able to
upload .mov format video and the image is also generated at
runtime.But other extention videos are not able to convert into .flv
format and image is also not generated. If we use ffmpeg command in
linux,it works properly.Do ffmpeg command work properly in windows?
Do give me solution to convert video in .flv format and generate