If you want to put your video files online using HTML5 then it's recommended to have three different formats for a full browser support. Those formats are mp4, ogv and webm.
If you are afraid of being hacked or someone else using your Facebook account you can enable option that will send you an email or text message in case your account has been accessed from a device that you never used before.
Central Russia got hit by meteor shower. It happened as the meteor exploded over the Ural, its pieces burnt in the lower part of the atmosphere but some were still able to hit the small town of Chelyabinsk.