On the Filepicker blog , they suggested using the extensions filter instead of mimetypes .
var acceptedExtensions = [ '3g2','3gp','3gp2','3gpp','3gpp2','aac','ac3','eac3','ec3','f4a', 'f4b','f4v','flv','highwinds','m4a','m4b','m4r','m4v','mkv','mov', 'mp3','mp4','oga','ogg','ogv','ogx','ts','webm','wma','wmv' ]; filepicker.pickAndStore({extensions: acceptedExtensions},...
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