To get the record from the parent node of the double click cell, try:
private void gridGroupingControl1_TableControlCurrentCellControlDoubleClick(object sender, GridTableControlControlEventArgs e)
{
GridCurrentCell cc = e.TableControl.CurrentCell;
GridTableCellStyleInfo style = e.TableControl.Model[cc.RowIndex, cc.ColIndex];
GridRecord rec = style.TableCellIdentity.DisplayElement.ParentTable.CurrentRecord as GridRecord;
if(rec != null)
{
object o = rec.GetData();//retrieves the object in the row
//if you are using DataTables, you can cast it to a DataView
Console.WriteLine(((DataRowView)o)[1]); // 2nd col in dataview
}