Oh, here I found it! All trains in that series are shown on this channel. The boxes are opened one by one (starting with the steam train) and each time a new loop is added and connected to the others in the way shown on the box itself. Cool!
https://www.youtube.com/watch?v=HHOOG1RopnI
https://www.youtube.com/watch?v=GOcV-pqlbF0
https://www.youtube.com/watch?v=pwnWVwQuOpo
https://www.youtube.com/watch?v=WFehhKwjr1s
https://www.youtube.com/watch?v=ymn_vHIF_OM
https://www.youtube.com/watch?v=mPr1DAOx7tg
https://www.youtube.com/watch?v=HHOOG1RopnI
https://www.youtube.com/watch?v=GOcV-pqlbF0
https://www.youtube.com/watch?v=pwnWVwQuOpo
https://www.youtube.com/watch?v=WFehhKwjr1s
https://www.youtube.com/watch?v=ymn_vHIF_OM
https://www.youtube.com/watch?v=mPr1DAOx7tg
My YouTube Channel: Mister No