File Browser on MAC - set file type filter, plupload

Question

I'm using plupload for uploading files to the server. Problem is with safari (6.0) on mac

In plupload there is parameter:

filters : [{title : "", extensions : ""}]

If I put following string in extensions "aac,wma", when I browse for files I will be able to pick-up any extension, and if I miss one of these, validation error will occur. And that is fine.

However, if I add mp3 or m4a to the list of extensions, I will only be able to choose one of those format (either aac or wma will not be available, it will be grey(disabled)). And there is no option to change File browser filter to "All files". Almost same thing is happening on Chrome(Windows) but there is option to choose "All files". On all other browser there is no problem like this one.

What to do with safari?

Thanks for help

EDIT: 1. screenshot from Chrome. You can see file filter is set to Custom files(only can see mp4, wav and m4a). I do not have safari(mac) currently, but same things is happening there, you just do not have this filter options:

2. Screenshot from my code, plupload extensions:

3. Something I found in firebug when inspecting element: