Bug: doesn't work under Windows 10.

# Bug: doesn't work under Windows 10.

This is my code:
```javascript
const ytdl = require('ytdl-core');
function downloadVideo(url, options, writeStream = null) {
const readStream = ytdl(url.toString(), options || { quality: 18 });
writeStream && writeStream.pipe(writeStream);
return readStream;
}

exports.downloadVideo = downloadVideo;
```
I'm getting good audio under Linux (Termux), but no audio at all under Windows. I checked, and I think whether or not FFMPEG is installed doesn't matter.