Hi Ed - it's better to upload the video to Vimeo or YouTube and just link to it here.

It is possible to directly upload an .mp4 video here, but there is only 50MB of attachment size set aside for every user, and video files tend to be fairly large and you will quickly run out of space if you try do it that way.

It's better to only directly upload things to the forum that aren't so large like videos tend to be.

- Michael