I was copying large files over to my computer for video editing and keeping an eye on available hard drive space I knew I should have had just enough space to put everything. However, as I was getting close to filling up my hard drive, the available free space suddenly jumped by about 30GB. Any idea what happened?
This can happen with Transactional NTFS. The free space is used for storing the transaction, once the transaction is committed the free space can be reclaimed.
The OS automatically emptied your trash, deleted TMP files, etc....
Happens on Windows and OS X.
What is your OS?