Click Add Photo/Video. anywhere on a post or video icon, and just select the video you want to upload. You can share your favorite YouTube or Vimeo videos. The maximum allowed video size is 250mb. Allowed file extensions for images/video are: jpg,png,jpeg,gif,mkv,docx,zip,rar,pdf,doc,mp3,mp4,flv,wav,txt,mov,avi,webm,wav,mpeg.