#2. There are a lot of considerations apart from bandwidth when it comes to disseminating information. For eg., having to use speakers or even reach for a set of headphones is reason enough for me to skip to the text.
[1] Sometimes video is more efficient than text. E.g. with respect to video games, gameplay videos can convey a lot of information in a short time. Basically if you want to teach someone about some system that changes over time, showing how it changes in video is often a lot clearer and faster than trying to describe it with words or static diagrams.
But a video that just involves listening to a person talk -- or, worse yet, read slides from a projector -- usually just ends up wasting my time compared to equivalent information presented as text.
[2] It's obvious that video consumes way more bytes-on-the-wire than text.