Adobe Primetime can request third-party ad servers over https even if the player is hosted on http. Only those ad-servers calls are upgraded to https that the client seeks during the Auditude Ad resolver phase.
This feature is not supported for Flash.
Use the following to enable secure ad loading. It is not enabled by default.
var auditudeSettings = new AdobePSDK.AuditudeSettings();
auditudeSettings.forceHttpsConfiguration.adServerCalls = true;