For hosting the app in ArcGIS Online, you could create a different message box than the one that contains the help and use that message box to display your splash content, including an embedded video. You'd have to pack the HTML for it into a single string, but, as you can see from the image, this still gives you flexibility. The only problem with this approach is that the message box does not have a close button; the only way to close the splash screen would be to click on one of the menu buttons in the top-right corner.[ATTACH=CONFIG]34784[/ATTACH](This snapshot uses the July 2014 release user interface update, but the concept can be used with the current application. The colors used for the non-hyperlink text and the background are controlled by the theme configured when the app is published.)To add this sample to your hosted app, you'd insert the following text between the '}' and ']' at the end of your configuration:, {
"classname": "js.LGMessageBox",
"styles": ".startMessageBox{display:block;padding:16px;position:absolute;overflow:auto;z-index:40;word-wrap:break-word;border:1px solid lightgray}",
"config": {
"rootId": "startMessageBox",
"content": "<h2>Getting Started with Finder</h2><hr><iframe frameborder='0' scrolling='no' width='720' height='405' src='http://video.arcgis.com/iframe/254/000000/width/720/0/00:00:00'></iframe><h3>Overview</h3><p>Finder is a configurable ArcGIS Online application that searches and queries attributes of feature layers. It can be used to present information about a wide variety of features such as property tax and assessment information or the locations of water access points.</p><p>This application can be deployed by local, state, and national governments; utilities; NGOs and private industries; and can be used by staff or citizens on desktop computers, smartphones, and tablet devices.</p><p>For more information, please go to the <a href='http://solutions.arcgis.com/local-government/' target='_blank'>ArcGIS for Local Government website</a></p>",
"parentDiv": "contentFrame",
"rootClass": "startMessageBox",
"horizOffset": [20, -20],
"vertOffset": [20, -20],
"trigger": "splash"
}
}
This sample sets the HTML content of the splash screen using the "content" parameter, places it over the map (which is inside the "contentFrame" parent), and sets horizontal and vertical offsets of 20 pixels from each side (so the splash screen will resize as the browser window resizes). Lastly, it sets a "trigger" of "splash"--this is the key to closing it whenever any of the menu buttons is closed.After making these changes to the configuration file, save and lint the file using validator such as JSONLint to ensure that you have well-formed, error-free JSON. It's also recommended that you clear your browser cache before attempting to view your modified configuration.