Application "residue" after restoring iMac to factory settings

So I restored my 27" iMac back to default settings. I wipped the drive clean but there seems to still be some residue leftover.

For instance, when I made a video in iMovie and uploaded to youtube. My previous video description and tags were there. There were no other projects or events in iMovie.

Also, when I donwloaded the tweetie client for the Mac. It seemed to have remembered some of my credentials.

I won't claim to know everything that goes on in the OS level of my mac. The explanation to this might be simple. But I thought that by wiping my drive I wipped everything. But I think I might know the reason.

I did not actually zero-out the data on the drive, I just deleted the dirrectory for it was faster. Is it possible that there was some data leak from the previous dirrectory?