To fulfill an item on my 101 things, here is my post about making a video post with your mac. My instructions are based on having a MacBook with a built in isight camera.
1. Open iMovie HD.
2. Start a new project. Pick whatever name you'd like. It should automatically save to your "movies" folder.
3. In the middle portion, there's a little slider with a camera and a pair of scissors. The scissors are for editing mode, and the camera is for filming mode. Just click on the slider to active your camera.
4. At this point, you should be able to see yourself on the camera. You're not recording yet. You can move around your monitor to aim the camera and get everything prepared.
5. When you're all ready, hit "record with isight." I recommend waiting a few seconds before you start in order to give yourself time to compose yourself. You can edit out any start snafus once you're done recording. (side note: if you wear glasses, you can reduce the glare by turning up the lights in the room and dimming your computer screen.)
6. Okay, record away. Say/do whatever you'd like. Go as long as you want (within reason -- at some point, you'll run out of hard drive space. Video eats up HD space quickly, but we can compress your video when you're completely done to get back a lot of HD space).
7. When you're done recording, hit "record with isight" again to stop recording. If you want to do more than one shot/angle/whatever, you can record a bunch of shorter clips now. Once you're done recording clips, proceed to the next step.
8. Now you get to edit your video! Switch to the scissors in that middle left slider you used before. You can now view your clips, make edits to them, and delete any portions you don't like. A few ways to do this:
a. Play your clip. Under the video part, you can see the seconds tick by. When you find a place you want to cut (say, if you want to delete a portion), go to "edit -> split clip at playhead" (or hit apple-T). The clip will split at the exact place you've highlighted. If the part you want to delete is in the middle of the video, you'll have to split the clip two times and delete the middle portion. To delete, just hit "delete" on your keyboard.
b. Deleting puts a clip in your imovie trash, so you can get it back if you need it. Just click on the trash icon (lower right hand corner) and drag the clip back into your clips frame. When you're done with the video, you should click on the trash icon and empty your trash, since this imovie trash is not the same as your normal trash.
c. You can reorder your clips by dragging them around.
d. If you hit the "editing" button in the middle right, you can add titles, transitions between scenes, put in video effects, or change the audio balance (fair warning: I've never used any of these, so I don't know how to use them. But they look pretty easy to use).
e. You can also add in your own music in the "media" tab. Another feature I haven't used. Definitely check out the help menu or futz around. iMovie is pretty darn easy to use.
9. If you want to see your whole movie, hold down the apple button and select every clip. They'll play in whatever order you've put them in.
10. Once you are completely done editing and are happy with your complete movie (really happy, since you won't be able to edit the compressed part), go to Share -> Quicktime. You can select the quality of compression you want. Save the compressed movie wherever you'd like.