This mod can act as a screensaver.

After pressing CTRL+S shortcut, the mod starts looking for new deliveries created by LTN. Press CTRL+S to disable screensaver.

After the delivery is created, mod transfers camera to the train and follows its. When the delivery is finished (the train has left the requester station) mod starts looking for a new train to follow. New deliveries for Items that were delivered in last N dliveries (N can be configured in per-player mod settings) are ignored when searching for the new train to follow. Transition time is also configurable via the per-player mod settings.

Mod probably doesn't work in multiplayer, with merged deliveries, can crash when a followed train is destroyed or player is killed while the mod is active.

Technology screen is disabled while the mod is active, so you can use mods like Auto Research to keep researching.

UPD: multiplayer and killing trains/player while the screensaver is active should not crash the game now.

https://www.youtube.com/watch?v=it5TYRX-glk small demonstration