The diesel video shows an Accucraft Baguley Drewry locomotive which has been converted to battery power using RCS radio control. The speaker was taken from an iPod external speaker unit. The black bonnet top was made removable to give easy access to the sound card controls.
The steam video shows a Pannier Tank from Garden Railway Specialists which has also been converted to battery power using RCS radio control. A plain 8 ohm speaker from an electronics store has been mounted in the plastic top of a paint spray can as a baffle. The boiler and panniers lift off for access to the electronics and batteries.