Unfortunately, no. You have to add all the extensions manually. I find it easiest to zip any non-mp3 files as is possible. Data integrity can be maintained more easily, and the file size is smaller (in most cases). It would be nice to have an "exclude" feature and have it be an either-or situation. Either you share all your files except for a few types, or you only share files of certain types and no others. Sounds like an open-source project assignment to me.
;-)