What are these wires?

Solution
Looks like a set of individually sleeved cables ... with Corsair, you can buy them straight from the manufacturer in various colors, or there are other places that sell them too.

http://www.corsair.com/en-us/professional-individually-sleeved-dc-cable-kit-type-3-generation-2-green


If I had to guess, I'd say this is probably the specific set, although there is no picture on the manufacturer's site:
http://www.corsair.com/en-us/ax1200i-professional-individually-sleeved-modular-cables-red
http://www.pccasegear.com/index.php?main_page=product_info&cPath=19_1424&products_id=23330&zenid=bfa5308547827f567d53640f665bc646


edit: You can only add them to your existing build if you have a modular power supply (one where the cables can snap in...
Looks like a set of individually sleeved cables ... with Corsair, you can buy them straight from the manufacturer in various colors, or there are other places that sell them too.

http://www.corsair.com/en-us/professional-individually-sleeved-dc-cable-kit-type-3-generation-2-green


If I had to guess, I'd say this is probably the specific set, although there is no picture on the manufacturer's site:
http://www.corsair.com/en-us/ax1200i-professional-individually-sleeved-modular-cables-red
http://www.pccasegear.com/index.php?main_page=product_info&cPath=19_1424&products_id=23330&zenid=bfa5308547827f567d53640f665bc646


edit: You can only add them to your existing build if you have a modular power supply (one where the cables can snap in and out from the side of the PSU.) Otherwise, you're stuck with the cables you have as they're built in to the unit. I suppose you could re-cover them, but that's more of a custom DIY crafting project.
 
Solution
mr taco is on the right track and since this is corsair made video i am going to assume everything in it is corsair as much as possible to show off the products they sell.

this is a question asked elsewhere as well. can you buy these cables from corsair or elsewhere and use them on a different branded modular psu? are the connections standardized to allow for this? they do look neat and would not mind getting some for my psu but only if they are a simple swap
 
These are custom sleeved cables. They are sleeved using plastic (PET) type sleeving amterials or paracord is also used.

There are a few ways to get this look, you can order exntesions from stores online, or for modular power supplies you can get the cables themselves. This is fairly simplke for popular PSUs like Corsair units. For a complete power supply plan on spending $100-200.

Single sleeving cables is an art form that takes a lot of patience and years to master. Here's a link to the master Lutro0's guides.

http://modbunker.com/guides/

Here's a link to where to buy cables:

http://www.performance-pcs.com/cables