That particular path does not appear in the Options Dialog, yet the Dynamic Blocks show up. I went looking deeper and deeper and eventually found the dynamic blocks are also at
c:\autodesk\AutoCAD_2014_English_Win_64bit_dlm\x64\en-us\acad\Acad\Program Files\Root\Sample\en-us\Dynamic Blocks
(How about that for a mouthful!) Now - That path is not in the Options Dialog either, but when I copied your file into that folder it came up in Design Center. This behaviour might be hard-wired somehow into the Student Version of AutoCAD 2014 I am using, but it does strike me as unusual. However, now I know where it is.
Unfortunately, I can't do anything with it. Under the DWG folder, under Blocks, I find OHD. It does not drag and drop onto the drawing area as other blocks do.
How do I use it?