What do you mean that’s not how it works?
The links to the clips
Youtube: https://youtube.com/shorts/7Iy3pp5uPXA?feature=share
Tiktok: https://vm.tiktok.com/ZMYpUJy2C/
I find that if you have the option of "display previews of links?" checked, it works easier. Also it helps to put your link in its own line rather than in the same line as text. Example, press enter twice to go to 2 new lines.
It should work like this.