I wouldn't ordinarily pimp my own (poorly made) video, it's not even monetized, but I have the only TI-99/4 demonstration on YouTube if you're interested:
I'm sorry, but I genuinely don't understand what you mean. There are thousands of videos of people demonstrating use of this computer. Is there a specific property of a demonstration you are looking for?
https://www.youtube.com/watch?v=oBgxOaUU7lQ