How to install the __mitmproxy__ certificate authority in Windows 7:

1. Copy the ~/.mitmproxy/mitmproxy-ca-cert.p12 file to the target system.
2. Double-click the certificate file. You should see a certificate import wizard:
3. Click "Next" until you're prompted for the certificate store:

4. Select "Place all certificates in the following store", and select "Trusted Root Certification Authorities":

5. Click "Next" and "Finish".