The "gform_file_upload_markup" filter can be used to modify the HTML for the multi-file upload "preview".
The filter gform_pluploads_settings allows the initialization settings(file size, file count, browse button, drag and drop, and more) for PlUpload to be changed.
The filter gform_form_args provides the ability to modify the options used to display the form.
The gform_entry_is_spam filter is used to mark entries as spam.
By default the real location of an uploaded file is hidden. The download URL will be generated with a security token to prevent guessing or enumeration attacks to discover the location of other files.
The gform_get_entries_args_entry_list filter is executed immediately before entries are fetched for display in the Entry List view.
The gform_file_path_pre_delete_file filter is executed before an uploaded file (from the File Upload or Post Image fields) is deleted from the entry.