You can create 16:9 widescreen DVDs in both DVD Studio Pro and iDVD 5. On a widescreen television, the video image will fill the entire 16:9 screen. If you play a widescreen DVD on a player connected to a standard 4:3 TV, the widescreen image should be presented "letterboxed," with black bars appearing above and below the width of the image to preserve the aspect ratio. However, some DVD players may not display widescreen DVDs (created in DVD Studio Pro or iDVD 5) in the correct letterbox presentation on a 4:3 TV or monitor.
If this happens to you, verify your DVD player setup. If the player is set to output video to a 16:9 monitor, letterboxing will not occur on 4:3 monitors. If you can, change the player's output for a 4:3 monitor so that it letterboxes correctly.
Note: Some players will still not present widescreen video with the correct letterbox presentation on a 4:3 TV or monitor. Additionally, menus burned from iDVD 5 are always 4:3 - the issue described above only concerns the widescreen content part of the DVD playing back as "stretched" on a 4:3 TV.