I suppose v could be elsewhere in the string though.
Range("C2", Range("C" & Rows.Count).End(xlUp)).Offset(, 1).Formula = _
        "=IF(ISNUMBER(FIND(""("",C2)),MID(C2,FIND(""("",C2)+1,FIND("")"",C2)-FIND(""("",C2)-1),"""")"