hi userht, as it is described at Mixed content blocking in Firefox a grey lock with an orange triangle means that mixed content blocking is NOT in place - this is just making you aware that a secure site also contains insecure passive elements, like images. if you have a particular problem with netflix, that must have a root cause different than mixed content blocking...

You can see a special padlock at the left end of the location/address bar.

• a padlock with a strike through means that mixed active content is blocked.
• a padlock with an exclamation mark attached means that mixed passive content (e.g. images) is present, but not blocked.
• https://support.mozilla.org/kb/control-center-site-privacy-and-security-firefox

The orange triangle with the exclamation mark is only a warning to tell you that mixed passive content like images coming via an open connection is present on the page. Firefox doesn't block mixed passive content by default, but you can check in the Web Console ("3-bar" menu button or Tools > Web Developer) to see what content this is about.

See also:

• https://developer.mozilla.org/Security/MixedContent