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Comment by djf1 | Hacker News Reader

You mention pause+rewind as a killer feature. Another nice feature is the ability to watch at a faster or slower pace (I usually watch 1.5x). These conveniences have made it such that I strongly prefer watching taped lecture to physically attending class. Add to that the fact that you can almost always get a faster response from posting in an online forum (often Piazza for my Stanford CS classes) than attending overcrowded and understaffed office hours. Most of my education has already moved online.

Even if online class doesn't make professors extinct, I think it will certainly make physical class time a thing of the past.

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Yes! 1.5x is fantastic! It solves the impedance mismatch inherent in human speech. 90% of what is being said takes 5% brainpower to process while the remaining 10% takes 300% of available brainpower. If you have to listen at 1x speed you are either bored and sleepy or falling further and further behind, sometimes both. The pause button solves the falling-behind problem and 1.5x speed solves the boredom problem.

"90% of what is being said takes 5% brainpower to process while the remaining 10% takes 300% of available brainpower."

I'd argue that's the result of poor communication, not any deficiency in human speech generally. Granted, it's very very hard to construct something with the right level of addressable information at every moment. But when it's done right it is glorious. I think one of the things people implicitly recognize in good communicators (not necessarily good orators, but good communicators) is their ability to tailor what they're saying in this way.

Variance in the backgrounds of your audience and variance in the physical state of your audience (tired, sick, etc) places a strict upper bound on how well you can communicate. If one student isn't experiencing an impedance mismatch, you can probably find another that is, unless the class is extremely small and homogeneous. Pause+rewind is robust to these problems.

I find that the phrase "pause+rewind" doesn't quite give the right impression; sure, sometimes you missed a sentence and need to rewind, and that's great. Other times, I'd like to fire up an editor and type out the code the lecturer's showing (I'm often surprised at how many things my mind missed just skimming the slide), see if it compiles, how it behaves for 10 minutes or so. Kind of like a self-imposed mini lab, if I'm feeling a bit behind on the topic at hand.

Other times, it's great to play it at 1.5x, or even skip sections entirely. E.g. if I'm comfortable with the topic / environment, I don't want to sit through 20 minutes of setting an IDE up, or a walkthrough of "hello world". I wonder if it would be possible to deviate from the strict linear progression of lectures, and allow the learner to choose. The difficulties in prerequisite knowledge might outweigh the benefits, but it might be an interesting idea. More of a library of closely related lectures and information, rather than a single course.

Another feature that I have found to be quite useful is when I don't quite grok something, I can often quickly jump over to a lecture from a completely different person on the same subject. That alternative perspective can make it instantly clear.

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