While not all of these tools are open source software, none of them use proprietary formats. In other words, the files created using them are able to be edited with other tools. For your open content item to be considered truly "open," the source file needs to be available and edit-enabled.
When hosting on a site like YouTube, it is good practice to provide some sort of contact information and an offer to provide the source file upon request.
Some of the information on this page came from the LibGuide titled" Open Textbooks, and Creative Commons" by Sarah Morehouse(Suny Empire State College) is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.
"OpenSource.com" is licensed under CC BY 4.0