MySimpleShow is a great tool for creating explanatory videos. Students have to create a script in order to produce a video through MySimpleShow. MySimpleShow just introduced a new option for creating and using scripts in the production of videos. The new option lets students upload PowerPoint files and use the contents of those files as their scripts.
http://www.freetech4teachers.com/2016/10/mysimpleshow-adds-convenient-new-way-to.html