(Edit: It's now slightly more open source, and while I'm not very familiar with exe building, the entire actual program seems to be missing, this is building a shell. Why not just post the project?)
Requires external program to work, fine. What's less fine is that although it claims it's open source, the source is nowhere to be found on Github. The zip-file he's labeled as "source" in releases only has a config file and the HTML used to explain that "it's totes not a virus and 300kb is too small to fit one in" (you could. Another red flag).
I wouldn't mind closed source, but when it claims to be transparent, and it's not, that raises red flags. The exe is also not signed by MS and flags up as adware in some antivirus software (may be false positives). Point is I don't trust it, and I don't think you should either. Releasing the actual source would probably fix this concern.