If you would like to add additional content to a specific module, you would need to edit the related html page to include the link and html code. Also, upload the video for example. You may ssh into the device to load files. The path to the modules depends upon each device. CAP3 modules directory is /.data/RACHEL/rachel/modules/
You can create your own module and load the module onto your device: http://community.rachelfriends.org/c/content/creating-modules
Or, you may use the Local Content module (link to user guide on the module). Finally, you may use Moodle.
There are a number of users on this form which have used one ore more of the options.