One way you could make both videos play sequentially and with sound on a single page would be to use a button, a multi-state object (MSO), and the in5 Video widget. The button would be set up to play the first video, the Video widget would include an end action that affects the MSO, and the video in the MSO would be set to autoplay. Here's how:
- Place both videos on the page.
- Make a button (it could be less conspicuous like a button that says "Start").
- Assign a Video action set to Play the video that should play first.
- Select the second video.
- Go to Window > Interactive > Object States and click the + button at the bottom of the panel to convert the select to an MSO (InDesign will duplicate the video so that there are 2 states).
- Select State 1 in the Object States panel and go to the Layers panel where you can twirl open the MSO to access the state and then the video that is on that state.
- Either replace the video with a poster image you've created separately, or use Object Export Options to convert the video to an image by doing the following:
- With the video selected, go to Object > Object Export Options.
- Select the EPUB and HTML tab.
- Set Preserve Appearance From Layout to Rasterize Content.
- Set the Format (PNG will maintain transparency).
- Set the Resolution to 150 for High Definition or 72 for Standard.
- When you export (in5 > Export HTML5 with in5...), go to the Advanced section of the export dialog and set Image Quality to Use Object Export Settings.
- Select the video in State 2 and go to in5 > Interactive Widgets > Video to set the following:
- Auto Play - selected
- Mute - deselected
- Select the video that should play first.
- Go to in5 > Interactive Widgets > Video and set the following:
- Autoplay - deselected
- Mute - deselected
- Loop - deselected
- End Action - Go to State and in the Select an MSO dialog that appears, select the MSO and target state that includes the 2nd video