These rooms use an LED lighting kit from LIT named Urban Underglow. It adds a great deal of color to any room, though it's important not to overdo it. Basically, this can be done with any LED lights in tube format that can easily be mounted underneath furniture. That makes us think of Christmas lights for some reason. What's interesting in this kit is that you can set it to a specific color, which is kind of the goal here. Having them cycle through colors is a bit too tacky.
The kit also comes with a remote control, which can come in handy. However, the price makes us think that you can probably wing your own LED tubes for a lot cheaper. The basic set sells for $210, which includes a 37-inch LED tube, mounting hardware, power suppl and a remote. Additional tubes can be purchased from $75 to $88. There is even a rechargeable battery pack to get rid of messy wires.
LED strip lights are widely available and you shouldn't have trouble finding them in a hardware store. This will probably be a lot cheaper than using LIT's solution. Naturally, you might not have the remote control and the possibility to cycle through colors, but it's the end result that counts. We can imagine some really cool effects, in dark rooms with white or blue lighting to give a somber room a bit more diffuse lighting.