Since we couldn't find any video of the full ep, I decided to do some screen captures:
What really threw me off at first: the supposed exterior of the house, which is clearly not Greystone:
(http://www.dsboards.com/images/Ment-1.jpg)
But as we all know, in the world of Hollywood magic, the exteriors and interiors are quite often not the same house. And on to those interiors:
(http://www.dsboards.com/images/Ment-2.jpg)
The "drawing room".
(http://www.dsboards.com/images/Ment-3.jpg)
(http://www.dsboards.com/images/Ment-4.jpg)
Two views of the "dining room" (which was used as a study on The Mentalist.
And if I hadn't been certain that the interiors were actually Greystone, once the flashback scene came up, I certainly would have been because of -
(http://www.dsboards.com/images/Ment-5.jpg)
The telltale decorative support for the minstrel gallery in the "drawing room".