If you want an intro video to appear when loading up Kodi you can set this in the Startup Wizard section here:
Startup Wizard -> Artwork -> Add an intro video
Similarly if you prefer to use a splash image rather than a video you can also set that here:
Startup Wizard -> Artwork -> Add a splash screen
Yes we understand that's a rather strange place to have this setting as it's not strictly anything to do with the Startup Wizard but it's a legacy setting which existed in the original Startup Wizard so for now it's staying in here until we find a better place to move it.
When adding an intro video we recommend using a very short video, certainly no longer than 10 seconds. This shows every time Kodi loads/restarts so if the user installs any third party content which regularly causes system crashes a long intro video can soon become very frustrating for them.