As the title says, the demo recorder mod found in the resources tab is creating a file to dump the .dem files but not actually recording the .dem files. After each run, every file is empty, no .dem files.

One thing to note is that the mod appears to be running the "record" command with no arguments based on these lines the console recorded during a short test run. http://pastebin.com/sBH7Pc6A

It had worked perfectly fine until lately... I'm not sure what I did to make it stop working.

What do you use to record demos ? There is no "demo recorder mod", only a "demo recording tool" by Maxxuss. Are you sure you use it correctly ? As you said, yes, it seems like the script is running the command "record" without any argument. Try to uninstall and reinstall again. If it doesn't work, ask Maxxuss.