Think only a mysql query will satisfy the need to know info.
On the DB for the Moodle try:
select contenthash,filename,filearea,filesize from `mdl_files` where (`filearea` like "backup" and `filesize` not like "0");
What one is looking at is the meta data. The actual file is located in the moodledata/filedir/ (contenthash is the 'clue') unless automated backups have been directed to a directory outside of moodledata.
'spirit of sharing', Ken