Funny thing about this video is that here at Digital Diner, we designed a very similar system several years ago. At the time, the RFID tags and readers were too big and expensive to be practical, so we've adopted another approach. When we buy socks we buy several identical pairs of socks. That way pairing goes faster, sorting whose socks are whose is much easier and if one goes missing, you still have plenty of ways to pair up the remaining ones until more of them goes missing.
Still, I like the smart socks form blacksocks.com and especially the feature (which is another one of the ideas we had too) that lets you monitor the number of wash cycles your socks have been through. Also, we assumed that there is no need to stop with socks. It should help you track the rest of your clothes. It could help you decide on what tops that match your pants are clean and available right now. It could even lead to a machine that sorts your laundry for you. The possibilities are endless.
If the concept of smart socks thrills you, they are available here.