Some things worth considering:
Like others are saying, stick to the topic you were asked to present. I have rarerly heard of any presentation were they gave too little information, most of the time it's the opposite. If your audience leave with a good experience, they learn and are more open to similar presentations later. Too much information and they leave learning little and will likely oppose similar presentations in the future.
Give real life examples! It's obvously very easy to dig up highly relevant cases and news articles etc. Create a good but short summary of any articles you include. The summary should highlight the issues and consequences that relates to your topic. And be sure to include various ways in which the company was exposed or individuals embarrassed etc. The most basic human instinct is fear, appeal to it by letting them know that one of them can end up loosing their job and/or embarrassed on the front page of the news as a result of their actions online. Putting the audience in the hot seat so to speak. The point is that I think it needs to directly relate to them individually, if consequences only relates to the company, many will forget/ignore.
Let them know that absolutely anything that get's posted online about them can live online as long as they live and probably longer. As was the case with pictures on Facebook.
I also think that a good opening to the presenation creates attention. Humour is what many choose, but do whatever feels natural, constrained/forced humour rarely works well.