She made several interesting points about how companies often delete files because they really can't afford to copy and store everything on the Internet forever.
However, we can never be certain if something we produce has been truly deleted. When we produce something on the Internet, it suddenly exists outside of our control. We no longer can decide who sees what–even with privacy settings because people can share screenshots.
Yes, the idea that everything we produce on the Internet will always be available is probably exaggerated, but the fact that anything we produce has the potential to reappear is still a scary and sobering thought.
It's certainly scary enough to keep me from posting pics from this weekend.