contextmenu.xaml

                    <Button Tag="{Binding RelativeSource={RelativeSource AncestorType=Grid}, Path=DataContext}" 
                            CommandParameter="{Binding}" 
                            Command="{Binding RelativeSource={RelativeSource AncestorType=Grid}, Path=DataContext.CmdPlayMeAtBookmark}" Margin="5,0,0,0" Style="{DynamicResource HyperlinkButton}" 
                            Content="{Binding Seconds, Converter={StaticResource SecondsConverter}}">
                        <Button.ContextMenu>
                            <ContextMenu Tag="{Binding}" DataContext="{Binding Path=PlacementTarget.(Button.Tag), RelativeSource={RelativeSource Self}}">
                                <MenuItem Header="Delete" CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.CommandParameter}" Command="{Binding CmdDeleteBookmark}" />
                            </ContextMenu>
                        </Button.ContextMenu>    
                    </Button>