Create video introductions for chapters

[david-a-wheeler]

In the course feedback: #83
there were requests for some video ("1. video"; "multimedia"; "Add some video content just to break up the reading."; "add videos and maybe some hands-on labs for the vulnerabilities"; "More videos, code examples").

We intentionally don't make this all video, even though I had originally intended to do that, because it's hard to do group reviews & updates of video. So instead, let's create several small video introductions to various chapters. That won't have to be updated often, yet will provide more variety in media.

I intend to write the short video intros first, then create videos using an on-screen (software) teleprompter and webcam. I'll probably use Zoom to record it.

Here were recommendations from Flavia:

Regarding video intros, the biggest one would be to not mention the chapter number, just the chapter title, or even more generic, like "In this chapter/section, we will discuss.....". This will allow us to reuse the videos both in edX and the LF training platform, and if the chapter title will be modified at some point, by not mentioning it, it may not need to be redone.

Video specs to use - the two highlighted ones are most important:

• 1920x1080
• 29.97 fps
• H.264.mp4 codec
• audio: AAC 44.1/192 kbps