Top questions were:
Will Facebook to take up challenges like blood donations in the near future?
If Facebook already existed, what idea would you be working on instead?
Can you post more pictures of your dog, Beast?
Does Facebook have any plans to work on something outside of internet technology?
How do you attract and select the right people to work at Facebook?
How will you improve your process of taking some things off of Facebook and leaving other things up?
You can see the answers in the video below:
Thank you Mark!