[bugwelle]

Is it not intended for this version to work on El Capitan OS?

Because I don't have macOS El Capitan, I can't test it, so I'm not sure about that. But officially El Capitan is not supported by MediaElch because Qt (the framework that MediaElch uses to create the user interface) only supports macOS 10.12 and above, see: http://doc.qt.io/qt-5/supported-platforms.html#macos
For macOS we use the latest version of Qt available on Homebrew (https://brew.sh/). MediaElch works fine with older versions of Qt, so in case MediaElch won't start on El Capitan, I could publish an "unofficial" version for it ("unofficial" because I can't test it). Just let me know :-)
 

Is there any way to do a select all and batch select movies?
Why can I Ctrl-A music but not movies?

You found a bug!
I've opened an issue for this on GitHub: https://github.com/Komet/MediaElch/issues/647


Regards,
Andre