There are three issues I identified:
1. When trying to connect using "HTTPS" url and WinAPI (InternetOpenUrl), I get an "ERROR_INTERNET_CLIENT_AUTH_CERT_NEEDED" error. I think something is misconfigured server-side, why does the client need a certificate?
2. If I try to use http, the web server redirect to https and corrupts (duplicates) the parameter list, possibly breaking backward compatibility with some apps using the API, you can test this in a browser.
3. Why are you forcing HTTP to redirect to HTTPS on the API? If the user doesn't care about encryption/privacy and cares more about speed, HTTP should be the way to go as HTTP queries are a lot faster than HTTPS.
For TheMovieDB plugin I implemented, I made it a user choice whether to use HTTP or HTTPS.