Open a new topic.
Give it a title in the Subject box.
Make sure video is in mp4 format for this to work.
Simply upload or drag the video from wherever it is on your computer, into this box. It will appear down below. Once it has loaded the status circle will turn green.
Click Place inline, and it will appear in this box. Hit the submit button.
Be aware, there is no size control, therefore it may look strange on smaller resolution displays. If so, click the button on the bottom right hand of the video (The square with four arrows) to play full-screen or use the horizontal scroll bar at the bottom to get to that button.
Once you post it, it may sometimes take a second or two, or 7, to play the video when you press play.