Support for multimedia in help dialogs has been added to Web Apps and App Preview. This has been implemented in Formplayer and CommCare HQ.
The latest version of Formplayer needs to be deployed before the change is introduced to CommCare HQ, in order to avoid errors in forms that use this functionality.
Action required: Please deploy Formplayer before June 20. You can find instructions here: Managing The Deployment — CommCareHQ Deployment documentation
On June 20, the code changes to CommCare HQ will be merged into the codebase. The new functionality will be available once CommCare HQ is deployed after June 20.