Hi,
Normally, users could pin the applications list under all apps after pressing start button and it will pin to start as live tile.
But besides apps, there are also some other things could be added like:folders, websites, settings shortcuts and so on. All of them will have the feature of "pin to start" when right cliking the page or button.
For the video you would like to add as tile, please check if there is option of "pin to start", which supposed to be the only way of adding tiles.
Reference links:
Exciting Updates to the Microsoft News App: From Live Tiles, to Weather Cards, to Video Hub
https://blogs.msn.com/microsoft-news-app-tiles/
How to Pin Folders, Websites, Settings, Notes, and More to the Start Menu on Windows 10
https://www.howtogeek.com/233297/how-to-pin-folders-websites-settings-notes-and-more-to-the-start-menu-on-windows-10/
Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.
Hope this helps and please help to accept as Answer if the response is useful.
Thanks,
Jenny