High quality, studio-grade reverb processor (...quoting from The SoundOnSound review of the M4000)
"...the Reverb 4000 is a top-notch reverb processor
...The Reverb 4000 essentially contains the most sophisticated and popular stereo reverb algorithms and presets found in the Reverb 6000
...we are talking about a collection of the best of the best reverb algorithms
...a key element of the Reverb 4000 is the provision of instant, real-time control through three dedicated rotary controllers. In addition, the unit can be controlled via a USB interface from a computer running supplied TC Icon software (downloadable here tcelectronic.com/downloads.html)
...The word which immediately springs to mind after using the Reverb 4000 for a short time is 'fabulous'!
...The user interface is sublime, and enables both superficial tweaking of the key parameters and detailed editing of in-depth parameters with equal aplomb and ease of access.
... In terms of the sonic quality of the VSS4 reverbs, the user interface, and the connectivity, the Reverb 4000 really must be considered the new class leader in stereo reverb processors
... This device redefines the state of the art for high-end stereo reverberators, but at a cost which is within the grasp of serious home studios"

see the full SOS review of the M4000 online.

includes the IEC power cable.

The YouTube video includes a dry (no reverb) cheesemo track. Reverb is added to the left channel, then to the right channel, then both ...then the reverb decay is manually reduced as the track plays ...so that you see audio in/out of each channel is working, and that the processor is responding correctly to real-time adjustment - it's ready to go.

It's priced realistically for what it is, it's quality and scarcity.