Its very easy. Change HTML as follows.

HTML

<asp:FileUpload ID="FileUpload1" runat="server" />
<asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="Upload" />
<hr />
<asp:GridView ID="GridView1" Visible="true" runat="server" AutoGenerateColumns="false">
<asp:TemplateField>
    <ItemTemplate>
        <u>
            <%# Eval("Name") %></u>
        <hr />
        <video id="VideoPlayer" src='<%# Eval("Id", "File.ashx?Id={0}") %>' controls="true"
            width="300" height="300" loop="true" />
    </ItemTemplate>
</asp:TemplateField>
</asp:GridView>

Then in code just replace these 2 lines.

DataList1.DataSource = cmd.ExecuteReader();
DataList1.DataBind();

with

GridView1.DataSource = cmd.ExecuteReader();
GridView1.DataBind();