If your Mac has an external DVD drive, watching movies on your screen couldn’t be simpler: Just insert a movie DVD. Unless you’ve fiddled with your preference settings, the DVD Player program opens and begins playing the movie in Full Screen mode. (Even the menu bar disappears. To make it reappear, move your cursor to near the top of the screen.)
If DVD Player doesn’t open automatically when you insert a DVD movie, you can open it yourself. It’s sitting there in your Applications folder. (Then fix the problem, using System Preferences→CDs & DVDs.)
Once DVD Player starts playing your movie, you can move your mouse to the bottom of the screen, at any time, to bring up the control bar.
Or just use the keyboard controls, which appear here in this clip ’n’ save cheat sheet:
Shift-⌘-, Shift-⌘- (press repeatedly to cycle to 3, 8, 16, and 32 times normal speed)
Skip forward/back 5 seconds
Full-screen mode on/off
Half, normal, maximum ...