The object reference is always Page relative, so binding doesn't work against local variables, only against properties of the form. Form properties that are bound should be marked public or protected, but not private as Reflection is used to get the values.
This or me is implicit, but can be specified so "Customer" or "this.Customer" is equivalent.
public string BindingSource { get; set; }
// Bind a DataRow Item bi.BindingSource = "Customer.DataRow"; bi.BindingSourceMember = "LastName"; // Bind a DataRow within a DataSet - not recommended though bi.BindingSource = "this.Customer.Tables["TCustomers"].Rows[0]"; bi.BindingSourceMember = "LastName"; // Bind an Object bi.BindingSource = "InventoryItem.Entity"; bi.BindingSourceMember = "ItemPrice"; // Bind a form property bi.BindingSource = "this"; // also "me" bi.BindingSourceMember = "CustomerPk";