You need to play the entire course content and then perform screen-capture in order to convert it to the HTML5 format even if the source files remain unavailable. The recorded outcome would get saved in the MP4 format and this is an HTML5-friendly format. Another way to deal with this issue is to make use of the decompile software so as to get the assets extracted from SWF. These assets can be used to redevelop the course content from scratch.