The general idea on the web appears to be that video/audio are to be separated with plain text. By separated, I mean you have a place that plays video/audio and a place that you read text. This is because it is widely understood that they are vastly different. However, audio and video are just another way of communication, just like text. So why do we separate the two even if they are nearly the same thing?

Correct me if I'm wrong but, most tutorials are either plain text how-to's (wiki-style) or visual/auditory instructional videos (YouTube). Why aren't the two combined?

Or, if it's already been done can someone reply with the link?

This might be bordering off-topic and if it is off-topic then please point me to the right place so it won't be.

This might also appear to be an obvious question, however I'm not sure if this subject has really been deeply thought-out by more than a few individuals.