Here's an approximate quote from about 25 minutes in (on mobile clients):
"between latency, long connection, disconnects, just incomplete socket transactions are not very polite in terms of how TCP is being used so you don't always get your heartbeat or your acknowledgement or the termination of the connection. And so it really creates a lot of stress on your servers because they end up with quite a lot of crap that they have to maintain. And Node does a really great job of doing it all for you."
To be fair, he does go on to explain some of what it doesn't do for you though.
- They are a very distributed team and that seems to work well for them. Interesting to see at a large company like Walmart.
- The node.js framework they use (I believe they are the original authors as well) is http://spumko.github.io/
- There's a ton of upside in the network centric nature of node.js for them.
- They sound like a very competent, small team, so some of the successes can also be attributed to that, rather than necessarily be all thanks to node.js (despite my own bias)
- It's great to have such high traffic installation of node.js out there, since it brings up the production quality of node.js