When you see postings or comments with a timestamp, would you prefer to see xx seconds/minutes/days/weeks/etc ago or the exact time stamp? Why?
I prefer an actual date, simply because when looking at a screenshot 'X days ago' becomes meaningless unless you know when the screenshot was taken.
I prefer to see absolute time - if I'm commenting somewhere online, I'm probably not in tip-top cognitive shape and I usually check only every so often.