jeebus.
Just tested it again and it would appear you are in fact right. Wow. The first test did not show it so much in the area I was in due to a lack of sub-pixel detail, but it is horribly obvious actually. Even when not moving, the Very High flickers like crazy and has pixels moving in and out (which appears to be the dithered sampling).
Order: Very High AO 0XMSAA, Very High AO 4XMSAA, "ON" AO 4XMSAA
It would appear tha Very High AO is not being temporally filtered like the high version
![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
You can see the checkboard pattern dancing about even while sitting still. Also, the lack of local occlusion on the view model also visible in the .gif looks pretty bad IMO when set to "Very High".