We are using a VTT closed captioning file to add closed captions to videos we are uploading to the Moodle LMS. The closed captioning is functioning correctly on all browsers, except for Internet Explorer. The header seems to be interpreting the file incorrectly. This only happens when trying to view the video in Moodle. It works on locally and on other servers. Even after adjusting the htaccess file to include the MIME type, it still ignores it. We currently have a Javascript Polyfil in place for all versions of IE, but we are unable to turn off the captions, which is not ideal.

Steps to reproduce:
1. Navigate to moodle
2. Use example files I have attached to this bug
3. Click 'Add an activity or resource'
4. Select 'file' from the list of options under Resources section
5. Upload files (html and vtt files)
6. Save and view added content

Observed Results:
Videos play without the ability to toggle closed captions.

Expected Results:
Videos play with the ability to toggle closed captions on all version of Internet Explorer.