I opened a terminal window using the launch bar icon (next to the "Menu" button on Jessie) and typed in
sudo apt-get install omxplayer. After doing its thing without errors, it said that I already had the latest version and that nothing was installed. I looked through the main menu editor, but couldn't find it.
When I installed sdlbasic the same way, it showed up automatically in the main menu under PROGRAMMING. Likewise, I did
sudo apt-get install for Iceweasel, and it was right there under INTERNET. But when I tried omxplayer and motion, I couldn't find them.
How do I find and run them?