The nature of the fault is open to speculation, but for iPhone and iPad users they are currently unable to stream content from BBC iPlayer, Sky Go or the NOW TV platform.
Users it appears are able to browse and the fault only becomes apparent when they try to view content. The problem only affects iOS based devices, for example there are no problems streaming Sky content via the dedicated NOW TV hardware.
The suggestion to roll back the date by a day or two may allow people to stream content but can cause other apps to have problems. The current suggestion that this is linked to an expired certificate is plausible, particularly with the HeartBleed issue lots of certificates have been revoked and re-issued and thus apps may be in need of an update, or a newly issued certificate used to control DRM may not be correctly setup.
While a lot of the content affected is catch-up, there are people who use NOW TV subscriptions for their only access to Sky channels and if the outage goes on for a few days questions of compensation are likely to be raised for those unable to access subscription content.
Update 5:15pm The BBC appears to have fixed the iPlayer, tweet saying iPlayer. NOW TV on iPhone still returns an error when trying to start a stream.