Why does Netflix video streaming work so well?

Variable data streams, multiple CDNs, buffering, metric-gathering, and because we've been doing this arguably longer than anyone else and have the experience to support a large number of devices and connection speeds. Edit: Recently we announced Open Connect - http://blog.netflix.com/2012/06/announcing-netflix-open-connect-network.html - which will make it cheaper for ISPs to deliver Netflix's movies to their customers. The upside for us is that there will be more reliability which means less rebuffering / streaming issues.

Netflix does not use a conventional content delivery network (CDN) to cache their content nearer the client. They have designed and built their own hardware and software solution and struck relationships with internet service providers to host the petabytes of movies inside the ISPs. This prevents the ISP having to deal with thousands and thousands of their customers, in peak times, traversing their network and pulling individual streams over their internet connection.  Instead, the video is served locally from the ISP.  The concept is called Open Connect and you can read all about it here:  https://openconnect.netflix.com/en/delivery-options/

You may be coming at this questions from a technical side, and Yan's answer is very true, but I believe the root cause is actually in the business model. YouTube has been streaming video longer than Netflix, and has access to even more resources than Netflix, though as you say, it's not as good of an experence. The reason for this is that YouTube is free, you are not their coustomer, their customers are advertisers. This causes a different alignment of priorities. YouTube only needs to provide a minimum experence to keep viewers engaged to continue serving them ads, and is otherwise inclined to reduce the maginal cost of an eyeball as much as possilbe without significantly reducing the number of eyeballs. On the other hand, with Netflix, you are the customer, you pay them a subscription a month, and expect it to work, if it doesn't work to a certain expectation of quality (which is MUCH higher now that you're paying), you will stop paying and they will loose money. This causes them to focus their talents on making your experience meet or exceed that expectation. Different goals, different results.

I don't work at Netflix, so I can only speak as a user. I use Netflix quite a bit, so I've seen a bit of how it behaves when the bandwidth goes low. I think the key fact is that Netflix buffers quite a bit of content ahead. Just the other day my Internet connection cut out, and Netflix kept on playing the movie for at least 3-5 minutes. The near-HD quality degrades down to what seems like standard definition very slowly. Therefore I have a feeling Netflix tries to acquire a relatively large buffer of content when playing a movie. It may use it's own proprietary technology to do so - so that's why you may not see this happen anywhere else. Having this large buffer means that Netflix can keep on playing the movie while your connection slows down or cuts off. It can the restore re-buffer the content when your connection is restored. These are just my personal , user observations.

•http://Amazoon.com is used Netflix model for creating world class recommendation system. In this recommended system to use sophisticated machine learning algorithms that can grow to arbitrary complexity and can deal with huge amounts of data. In Netflix perform collaborative filtering .The data is to store it for later offline processing, which manages the offline jobs. Computation can be done offline , near line or online. •Online Computing ( Near Line) - Respond better to recent events and user interaction, but has to respond to requests in real-time. •Offline Computing - limitations on the amount of data and the computational complexity of the algorithms since it runs in a batch manner with relaxed timing requirements. •Hermes tool that provides all of these capabilities and integrates them into a coherent publish-subscribe framework. It allows data to be delivered to subscribers in near real-time. In some sense, it covers some of the same use cases as http://kafka.apache.org/, but it is not a message/event queue system •Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. •Scala is an acronym for “Scalable Language”. This means that Scala grows with you. You can play with it by typing one-line expressions and observing the results. But you can also rely on it for large mission critical systems, as many companies, including Twitter, LinkedIn, or Intel do. •Variable data streams, multiple CDNs, buffering, metric-gathering, and because we've been doing this arguably longer than anyone else and have the experience to support a large number of devices and connection speeds.

Actually those people who are using other video streaming sites, love to use them because that found it closer to them. Two of three people are using You tube or such other video streaming from a long time back, that's why they are reliable to it. Based on selection, price, interface, third party devices and quality – we came to the conclusion that Netflix is one of the most well-rounded video streaming services you’re going to find.If you’re still having a hard time deciding which of these services is right for you, one of the most important factors to consider when it comes to making this decision is the first criteria we used – the selection. Rather than search each service one by one to see if it has the movies or TV shows you like, with the following third party sites, you can search all four (and quite a few more) in one go.Even if you don’t want to choose one service over the other, the ability to search across online streaming and rental sites is incredibly useful. With Netflix, Hulu, Amazon, iTunes, Vudu, Crackle, and more, the following sites will let you know where you can stream your TV show or film from.Netflix, Hulu Plus, Amazon Play, Crackle, YouTube, Streampix and HitBliss for TV shows. In addition to these sites, it also searches Epix, Redbox Instant and Snagfilms for movies.If you are going to make your own video or you are in profession of broadcasting or live event, you can clear your path to success with the help of  Matrox Monarch HDXTo know more on features of this equipment, read more here - http://computersinfinite.com/broadcast-at-a-high-speed-with-matrox-monarch-hdx/