The secure page boundary
Modern websites use HTTPS to prevent network intermediaries from changing what users receive. If the player then requests an HTTP segment, that segment can be observed or modified. Browsers therefore block active mixed content instead of silently weakening the page.
Check the complete dependency tree
Changing the first manifest to HTTPS is only the beginning. Relative paths inherit its scheme, but absolute variant, key, subtitle and segment URLs may remain HTTP. Redirect targets also need inspection. One insecure dependency can stop the whole stream.
Upgrade at the CDN
The durable solution is end-to-end HTTPS with valid certificates and redirects that stay secure. Rewriting addresses in a directory cannot fix a server that does not actually serve TLS, and AdiosTV does not relay insecure media through its own domain.