How do I create a tag that is not automatically closed by chameleon?
The <source> element is an empty element so there must be no closing tag.
but no matter what I do it always comes back with a </source> and it keeps failing my accessibility test since it is considered a "Stray end tag"
here is what the code looks like <source tal:attributes="src download_url; type content_type">
I do not know about Chameleon, but pagetemplate distinguished between an HTML and an XML template. "empty element" is an HTML concept (more generally, you need a DTD to know about empty elements); XML tries to be usable without a DTD and then does not know about "empty elements". This implies that in an XML template the empty source element looks like <source /> or <source></source>.
Thus, Chameleon can be right, provided it has a good reason to treat your template as an XML template (most Plone templates are XHTML templates, which means XML templates).