Variable names appearing in final file name.

[HeySteets]

Checklist

• I'm reporting a broken site support issue
• [X ] I've verified that I'm running youtube-dl version 2019.06.08
• [X ] I've checked that all provided URLs are alive and playable in a browser
• [X ] I've checked that all URLs and arguments with special characters are properly quoted or escaped
• [X ] I've searched the bugtracker for similar bug reports including closed ones
• [X ] I've read bugs section in FAQ

Verbose log

<command removed, issue resolved.>

Description

I provided several variables in the name of the file, however they do not get replaced by the content they are supposed to, leading to just the variable staying in the file name, causing videos to overwrite others.

[dstftw]

Invalid template. Missing %.

[HeySteets]

Realized the file was invoked via batch, so it needed two %'s where you would only usually need one.