According to the Readme file for youtube-dl (the program you run as the file yt-dl.py), --write-srt is not an option, but --write-sub is. The Readme file with all options is available here: https://github.com/rg3/youtube-dl/blob/master/README.md#readme
I successfully downloaded a video with subtitles using yt-dl.py --sub-lang en --convert-subs srt --write-sub <youtube url>. --sub-lang en chooses english subtitles, --convert-subs srt converts the subtitles to the common SubRib (.srt) format, --write-sub writes the subtitles to a .srt file and <youtube url> is simply the URL/web address of the youtube video page.
An example: yt-dl.py --sub-lang en --convert-subs srt --write-sub https://www.youtube.com/watch?v=sWAN0FwfD5M
If you use the windows executable, launch your DOS-prompt, navigate to your youtube-dl.exe file and write e.g: youtube-dl.exe --sub-lang en --convert-subs srt --write-sub https://www.youtube.com/watch?v=sWAN0FwfD5M. The --convert-subs command will not work if you do not have the ffmpeg program installed. If that is the case, you have to omit this option and youtube-dl will output .vtt subtitles instead.
Best Answer
You can download the others manually at sites like http://www.keepvid.com/, but that could be very lengthy depending on how many more videos there are. If there are too many videos, I would recommend using some type of automation software to perform the mouse and keyboard actions for you. For windows 7, I think there's a variety programs that can do this.
To answer your question:
As far as I know, YTD cannot do this.