Now that your 01 Whistle button is working, you can safely generate the three remaining buttons. Use the following general steps to do so:
- Use the Ctrl + D (Windows) / command + D (Mac) shortcut to duplicate the 01 Whistle button.
- Change the text of the duplicated button so it matches the name of the corresponding bookmark.
- Change the action of the button, so it jumps to the right bookmark.
- When all four buttons are present on the slide, use the tools of the Align toolbar to properly align and distribute them.
At the end of this process, your slide should look like the following screenshot:
Of course, don't hesitate to use the Preview | HTML 5 in Browser icon on the Toolbar to give your new buttons a try. You should be able to jump back and forth between the four bookmarks you added on top of the video.