I tested twice. Below are the details from my second test. Bear in mind that TC updates usage hourly, and mine is updated at 43 minutes past the hour.
Between 16:43 and 17:52 this evening, as shown in my browser history, I visited many of the ‘unmetered’ sites and viewed many video clips. The remainders are static; they, at most, had small-sized photos. None had video or audio components that I could recall. In my opinion, the traffic to these static, non-ummetered sites would have accounted for no more than 5 MB in total.
Compare my browser history against my recorded usage for the same time period. As highlighted in green, I used 222 MB.
Even if we include the small lag between actual usage to the recorded usage, which shouldn’t have been much as my traffic immediately prior to 16:43 was light, there number still does not make sense.
From these observations, I am inclined to suggest that the so-called unmetered sites are actually metered.

Edit: uploaded the images but they didn't show. That's try thes two links:
https://cdn.geekzone.co.nz/imagessubs/blog47db4388b7c360eca6a0a83c91e01323.jpg
https://cdn.geekzone.co.nz/imagessubs/blog74072af68c1b858dd9864d97db92e916.jpg
