The phone scales everything to fit when playing video, so it’ll letterbox a 16:9 movie, which will be pretty gentle.

For further reading, see here and here.

OS X example: Disc Utility
Step 1. Click the Burn button.

Step 2. Choose a disk image. (The standard file extension for disk images is .iso.)

Step 3. Choose a speed and click Burn. Lower is better for audio and video; I never burn a video DVD at over 4x speed.

Step 1. Go to the File menu and choose Record CD from CD image.

Step 2. Pick ISO image files from the drop-down menu, and choose an image file.

Step 3. Choose a recording speed, enable Buffer Underrun Prevention, and click Start Recording.

There are plenty of sites that run down the technical virtues of the two sides and their various flavors. So here’s my advice based on my subjective experience with the lot.

1. Recommended: DVD-R, the oldest recordable DVD standard, has by far the best compatibility. I strongly suggest you stick to this when making discs to hand out to strangers–film festival submissions, for example.

2. Be Careful: DVD+R, the newer standard, is technically superior–greater reliability and faster read speeds–but doesn’t work on older video players and computers (any Macs made before 2004, for example). Use your own judgement, but I avoid them for that reason.

3. Sometimes Useful: DVD+R DL (“Dual Layer”) has nearly twice the capacity of ordinary discs, 8.5GB instead of 4.5GB. Their compatibility is spotty, but if you’ve got to hand off files to someone you know, it’s not a bad way to move data around. Just don’t give them out to the general public.

4. Waste of Money: DVD-R DL discs are still sold in stores, but I don’t know who’s buying them. I’ve never been able to either write or read one successfully. Unless you know something I don’t, avoid them.

5. Getting Obsolete: RW (“ReWriteable”) discs did a good job over the past decade. But they’re expensive, their compatibility isn’t the greatest, and you have to erase them for reuse. Buy a USB key instead.

Step 1. Put in your original disc and run Disk Utility from the Utilities folder inside your main Applications folder.

Step 2. You’ll see your CD or DVD appear on the left-hand side of the Disk Utility window. Click on it.

Step 3. Go up to the main menu and choose Images / New / Image from (name of your disc).

Step 4. Choose DVD/CD Master as your format, and then save it.

Step 5. Change the new file’s extension (the abbreviation with a dot and three letters that tells you the file type) from .cdr to .iso. This will make sure that Windows and Mac programs alike will be able to tell what it is.

Step 6. The “image” you just created isn’t a graphic; it’s a disk image, an exact copy of your CD or DVD saved on your hard drive. Instead of having to copy the disc by sticking in the original each time, you can burn a fresh copy in half the time by running Disk Utility, clicking the Burn button, and loading your disk image.

See here for more detailed Mac and Windows burning instructions.