Please help me understand cable internet technology.

There are two things going on: First, when your cable provider needs to provide the same exact stream to a few thousand customers, it can share the wires much more effectively than when it provides a free-flowing network stream to those customers. If a hundred customers are all watching the same TV show at the same time, they're all pulling down the signal for that one channel. If a hundred customers are all watching YouTube or Hulu slightly out of sync, that's a hundred different signals that need to go down some set of wires simultaneously. Second, the cable company has no business reason to give a third party the ability to deliver to you what you want to watch when you want to watch it. They have lots of business dollar reasons to deliver contracted shows with commercials intact when and where the programmers decide, so solving the "why does my Hulu show stutter" isn't in their best short-term interest.

Watching television is like sitting in a theater listening to someone give a speech. There's only one person, on one stage, speaking into one microphone, and yet everyone in the audience can hear it--even the people who are bored out of their minds that are trying to sleep. Now imagine if everyone in the theater decided to get up and individually ask the person on the stage to deliver the speech. And imagine if after every sentence of the speech, the person listening in said "uh huh" to let the speaker know that they had heard it. That's the Internet.

1 gigabit/sec of TV delivered to 1000 homes == 1 gigabit/sec of load on the distribution network. 1 gigibit/sec of internet delivered to 1000 homes == 1000 gigibit/sec of load. Because in the first case, all 1000 homes are receiving the same thing. In the second case, they're all different. And it means the cable company has to have a 1000 gigibit/sec connection to an internet backbone, too. Whereas the TV comes to them via satellite dishes.

On-demand service isn't "always on". What's happening with that is that a given area will have a certain number of TV-channel equivalents allocated to "always on", but far fewer than the number of custtomers. When someone orders an "on demand", they get allocated one of those channels for the duration of the program. Then it's freed up and can be used by someone else. On Demand is a lot like cell phones: you get a dedicated channel, but only as long as you're using it (and paying for it).

Some googling turned this up:I work in the cable industry and spend a fair amount of time with Comcast. I do know a a bit about their On Demand network. When you decide to watch a movie, your set top box (must be digital) sends a message to a video server located somewhere in your city. The server sets up a session with you set top box. A single digital TV stream (about 3.5 MB/s) is reserved for your use. Generally 10 or 11 of these streams fill a 6 MHz TV channel. This makes the On Demand system is a major user of network bandwidth. To allow any significant number of On Demand users, the network must be segmented -- different streams are sent to different geographical locations within the network at the same RF frequencies. There are many more details. But this is a high-level overview of how the system works.Which, on preview, fits with Chocolate Pickle's remarks.

(This is from my husband, a network engineer at a cable company.) Keep in mind that adding more and more HD channels is quickly eating up the bandwidth upgrades that cable companies have been adding over the years. Adding a channel cuts off bandwith on the core network. Even with this though, they are staying ahead of the game. Many providers are delivering well over 10m speeds and that wasn't around more than a few years ago. They're constantly investing to keep up. When you have service with a cable company, you're sharing bandwidth that the company has allocated to 10,000 or so of your neighbors. If a lot of people are on at once everyone slows down. You're specific problem is coming from a higher demand for bandwidth. More people want things like Netflix and Hulu now. Cable companies are not presently allowed to throttle down traffic to sites like those so if many are streaming from them, access to other sites will slow down. Not that they should do that, it's just a variable they're dealing with. Rather than getting worse, I think this is the kind of thing that will get better before it gets better.

zsazsa: your phrasing is starting to make sense to me. But let me see if I really understand it...let's say a neighborhood has 50 homes and the cable company has 50 channels. And each home is also allocated 1 channel-equivalent of internet bandwidth. That would mean the cable company is actually sending 100 "channels" worth of capacity to the neighborhood but each house only receives 51 channels worth. And if the cable company eliminated TV services and re-allocated the bandwidth, each house would only double its internet bandwidth (100 channel-equivalents / 50 houses = 2 per house, compared to 1 in the prior example). ..... So assuming I'm on the right track...do the cable companies' on-demand services act more like internet traffic than TV traffic? Or maybe something in-between if the data is hosted local rather than out on the net somewhere? I assume that content is NOT being streamed to everyone like a typical channel, but only delivered to a specific address when requested?

I screwed my comment up. ...certain number of TV-channels allocated to on-demand, but far fewer... My apologies.

Er... "your."