For the video, if a small Gif file, below 5Mb you can use insert image button. If you upload to youtube you can put its link by using the Youtube button (icon) or you can post to any video sharing site and post its link here. Just make sure to set to public.
Also perhaps try these setting. You probably set to Menu only, hence you can only change tab via the menu.. try those other 3 option.

Thank you,
Basj,
Stardock Community Assistant