Low level format
You cannot low level format an IDE or SATA drive. SCSI, ESDI and MFM, yes.
Writing zeroes to the drive with something like DBAN removes anything that is there. forensic recovery consists of using something other then the drives read head to analyze the platters. In general this makes it possible to determine what was previously written to the disk.
Oh, would you look at that. DBAN is exactly what is being covered by the video.
I might also point out that the "example" scenario that was played out in theat video is both contrived and ridiculous. a format/reinstall was obviously not performed.
a Format/Reinstall is enough, IMO, to make recovery of data impossible for about 90% of the population.