Board Thread:Support Requests - Getting Technical/@comment-33218110-20181226174402

I am trying to post a message on someone's message wall, but every time I click post when I finished writing, the post just disappears and I have to start all over again.

What's causing this?

''I also made a screen recording that was saved as an MP4 file, and when I tried to upload it here, it says that it is an illegal file. What files for videos are accepted?'' 