FileOutputStream out;
File land=new File(Environment.getExternalStorageDirectory().getAbsoluteFile()
                +"/portland.jpg");// image file use to create image u can give any path.
Bitmap bitmap=ThumbnailUtils.createVideoThumbnail(filePath,MediaStore.Video.Thumbnails.FULL_SCREEN_KIND);//filePath is your video file path.
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG,100,stream);
        byte[] byteArray = stream.toByteArray();

        out=new  FileOutputStream(land.getPath());
        out.write(byteArray);
        out.close();