So, adding a YouTube video to an MOTD, right? I did something similar for my gaming server once. What you need to do is grab the Embed'code from the YouTube video. Just hit Share under the video and click on Embed. Then you copy this code and paste it into your MOTD. It's a bit of copy-pasting, but it works.
For the buttons thing, it's a little more complicated. You're gonna need some basic HTML and maybe a touch of JavaScript. I made buttons once for a different project. They weren't perfect, but they did the job. Look up some simple tutorials online, they'll guide you through making these buttons that can switch between different MOTDs.
Oh, and for making cool stuff for your MOTD, I found this neat video editor,
https://www.movavi.com/mac-video-editor/. It's pretty straightforward and has some cool features that might help you jazz up your content. I used it for some of my own stuff, and it's pretty handy.