Currently, video upload isn't recommended, as the file sizes are too large to host directly on SchoolSpeak. Instead, it is recommended to upload the video to a dedicated video site like Youtube or Vimeo, and then embedding.
1. Go to what was posted on Youtube or Vimeo and then click Share
2. Then click Embed
3. Then copy the code snippet
4. Once you have that copied, go to SchoolSpeak to where you want to post it and HTML in the bottom corner of the content box
5. Then Paste and click Add or Update