Chrome.manifest resource file not loading certain files for Gecko Webbrowser
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I am using the Gecko Webbrowser plug in adding resources in the chrome.manifest file (actually the binary.manifest file but this is loading by the former), I am having an issue where I only seem to be able to load .png files. Using the same location with:

    resource filesLocations file:///C:/foo/

Using a picture like

    <img src="resource://filesLocations/foo.png"/>

Will display a picture from that resource file however 

    <video autoplay="autoplay" id="my_player" loop="" controls="">
       <source src="resource://filesLocations/foo.webm" type='video/webm; codecs="vp8, vorbis"' />
    </video>

Various reading on the subject said there are no security restrictions on files, yet the picture will load fine but the .webm video will not however I can't find anything in the Gecko code to suggest it has anything stopping the file loading. Does anyone know what is going wrong here?

(browser does support html5 just by the by)