I figured this out. I’m sure you moved on to other things, but this may help someone else.
If you firebug this popup, you’ll see that there are two instances of the that popup for some reason.
Quick fix:
If you open up:
/YOURplugindirectory/email-to-download/app/assets/js/admin/ed-admin.js
Somewhere around line 83 you’ll see:
var id = $(‘#etd_product’).val();
change this to:
var id = $(‘#TB_ajaxContent #etd_product’).val();
save, and it should work.
Hopefully they fix it in the next update, or else you’ll have to do this again.
Cheers