For the people that are doing the "subtitle" versions of the screencasts, I have made some basic research on SubtitleComposer, which is a KDE 4 application suited exactly for this purpose. Here I'll write down what I have found so far, to ease the work of the students.

First of all, you can obtain SubtitleComposer on kde-apps.org. Chances are that binary packages may exist for your distro already (in openSUSE it's in the Packman repository, with the name "kde4-subtitlecomposer").

After installing and running the program, you'll find that perhaps you can't do much at first. The first thing is to load a video, under the "Video" menu, "Open Video" option. OGV files produced by recordmydesktop don't show up in the filtered view of the file selector, so set it as "all files".

Once the video is loaded, you need to start adding subtitles. That's a little tricky. Push "Ctrl-Ins" or use Edit > Insert Before to generate a first line of text. Then click on it, and you can edit it in the text area underneath. After that you can use Edit > Insert Before or Edit > Insert After to add lines where you want.

How to time the lines? You can either insert manually the start, end and duration times (tedious) or you can use the icons next to the player window. Specifically, the third and second icons from the right set start and end point for the current line. Like that, you can play the video, pause it where you want to set the starting point, set it, resume, pause and set the ending point.

On the left of those two icons, there are buttons that allow you to jump from line to line in the video to see if things are OK.

To set subtitle font, font size and color, you have to go in the settings page, where you can also set your video backend. For this course, please use Free fonts for the subtitles. I'd say Dejavu Sans, or the equivalent from the Liberation fonts (if you have them). Notice that the fonts are not scaled in proportion to the video. You have to see them in full screen to see how they look, or if you target a small resolution, scale them down accordingly.

That's all. I hope this is helpful in producing even better quality screencasts!