RadEditor is closing the source element that is nested inside the video element . For example, in the attached screen shots show the “source” element which we add it to Rich text field. After we save the Rich Text field and open it again, we see the source element is closed. Is there a configuration setting that would allow us to bypass the closure of the source element?
I performed a test with an editable iframe and noticed that the browser strips the closing source tag.
To fix the problem you have to enable the ConvertToXhtml filter, which you have probably disabled since this filter is enabled by default. You can find yourself that the editor does not strip the source tag when the ConvertToXhtml is turned on in the following https://demos.telerik.com/aspnet-ajax/editor/examples/builtincontentfilters/defaultcs.aspx demo.