Why video and audio are analog or serial, and text is digital or parallel
I had the pleasure of participating in an interesting discussion on the value of text vs audio/video on avc.com yesterday. The gist: non-interactive multimedia (audio/video) are a powerful way to get information to consumers (in the sense that they consume information) over the Internet. They are also incredibly inefficient.
The last time I converted my old audio tapes and VHS tapes to digital, it took exactly as long as the tape. A one hour tape had to be played and captured by an audio or video capture device for exactly one hour. However, once digitized, I could transcode them, e.g. audio from wav to mp3 or aac, in far less than one hour.
The human mind, however, cannot "transcode" at anything faster than the rate of information received. In that respect, audio and video are "analog." For me to receive one hour of video information, I need to watch the YouTube video for exactly one hour. I can always choose to skip ahead to 0:42, but then I lose everything up until 0:42, not having watched it. Further, it is difficult to know exactly to where to fast-forward. For many types of information - entertainment, exercise videos, etc. - that may be just fine. For others, it is highly inefficient.
The alternative, as far as the human mind is concerned, is "digital" or text. If I see a page of text, I can skim it very quickly, since my eyes see all of it at once. I can gather information far more efficiently in this fashion, essentially operating at multiples of one hour of data in just one hour, and with greater confidence that I have read what I want to read. As heuristocrat pointed out, often three days of a conference can be summed up at high fidelity in just one hour of reading.
In the Internet, text, video and audio can all be in an analog or digital format; for the human mind, the ultimate purpose of all of the information, video and audio are inherently analog, while text is inherently digital.
A different terminology that heuristocrat drove me to consider is that video and audio are serial - we process them one after the other, in order - while text and images are parallel - we process multiple parts at once, "scanning, chunking and pattern matching" in his words. Either way, until we find a way to instantly upload video into our brains, text and images will continue to be the most efficient way to transmit information.