Firefogg "Select file" button goes grey, then does not move on to Options on Firefox 31 and Ubuntu 14.04.1 LTS

[David Ing]

I have previously used Firefogg on Ubuntu 12.04 successfully. On a new installation of Ubuntu 14.04.1 LTS -- which now uses libav as default rather than ffmpeg -- I have installed ffmpeg from https://launchpad.net/~jon-severinsson/+archive/ubuntu/ffmpeg and then used the Ubuntu Software Centre to install ffmpeg2theora.

When I select "Make web video", the next screen comes up as usual. When I "Select File", I can choose the MP4 file that I want converted. At that point, the "Select File..." button is greyed out, and the program does not move to the next step of "Options", which remains greyed out.

[lolisamurai (lolisamurai)]

Same here on Windows, Firefox 35.0.1.

browser console log:
Use of getPreventDefault() is deprecated. Use defaultPrevented instead. jquery-1.6.2.min.js:17
ReferenceError: File is not defined Firefogg.js:154
NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS: [JavaScript Error: "File is not defined" {file: "file:///C:/Users/Francesco/AppData/Roaming<email address hidden>/components/Firefogg.js" line: 154}]'[JavaScript Error: "File is not defined" {file: "file:///C:/Users/Francesco/AppData/Roaming<email address hidden>/components/Firefogg.js" line: 154}]' when calling method: [nsIFirefogg::selectVideo]

I have already tried reinstalling firefox or the extension.