I have a solution with only the aspx and not touch the cs backend
You can predict the render of template Column. Try this I suppose that the code status that indicate failed is "failed"
<asp:TemplateColumn>
<HeaderTemplate>
<b>Status </b>
</HeaderTemplate>
<ItemTemplate>
<asp:PlaceHolder ID="Ok" runat="server" Visible='<%# (Eval("LoadStatus").ToString()=="Failed"?false:true) %>'><%----%>
<asp:Label ID="Label1" Text='<%# Eval("LoadStatus") %>' runat="server" />
</asp:PlaceHolder>
<asp:PlaceHolder ID="Ko" runat="server" Visible='<%# (Eval("LoadStatus").ToString()=="Failed"?true:false) %>'><%----%>
<asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# string.Format("DataLoaderErrorMessage.aspx?id={0}",Eval("LoadedFileID"))%>'><%# Eval("LoadStatus") %></asp:HyperLink>
</asp:PlaceHolder>
</ItemTemplate>
</asp:TemplateColumn>