Issues with media elements in nested content

[cbcode1]

Describe the bug
When an HTML media element (i.e. <audio> and <video>) is inserted into nested content (e.g. in the Quiz, Branching Scenario or Interactive Video widget), toggling the "Autoplay" toggle in the options causes the audio to be played in multiple instances at the same time, interfering with itself. These instances cannot be stopped without leaving the editor, not even by deleting the media element.

To Reproduce
Steps to reproduce the behavior:

1. Insert the Branching Scenario widget.
2. On any page of the Branching Scenario, insert an "Audio" element and select a source.
3. Make sure your volume is not set too high to avoid unpleasant surprises.
4. Toggle the "Autoplay" toggle a few times.
5. Reload or close the tab or enter preview mode to stop the madness.

Desktop (please complete the following information):

• OS: Windows 11
• Browser: Google Chrome 144.0.7559.110
• WebWriter Version 1.9.4