(copied in its entirety from an entry by "floppus" over at Mark Watches, with permission)
Last week, some folks were having trouble because they were watching the PAL version of the movie, which runs slightly faster than the NTSC version that Mark was watching. To be specific, the PAL version runs 4% faster (25 fps rather than 23.976 fps), which means that by the end of the first half, you’ll be about 4 minutes ahead.
If you’re using a hardware DVD player, you’re probably out of luck. But if you’re playing it on your PC, there’s likely to be a way to adjust the speed so you can stay in sync with everyone.
If you’re watching the Blu‐Ray, I’m guessing it’s probably 23.976 fps no matter what country you’re in (can anyone confirm this?) The same goes for online streaming services.
How to tell whether you have the NTSC or the PAL version of the DVD:
• If you bought the DVD in one of the green countries on this map
, it’s probably the NTSC version, and you can ignore this message. If you bought the DVD elsewhere, it’s probably the PAL version.
• If you’re using VLC, select “Tools” > “Codec Information,” and look for the line that says “Frame rate.” It should say 59.94 for the NTSC version, or 50 for the PAL version.
• If you’re using mplayer, look through the terminal output for the line that begins “VIDEO: MPEG2.” It should say “29.970 fps” for the NTSC version, or “25.000 fps” for the PAL version.
How to play the PAL DVD at NTSC speed:
If you’re using VLC:
• Select “Tools” > “Preferences.”
• Under “Show settings,” select “All.”
• Select “Input / Codecs” from the left‐hand pane.
• Under “Playback control,” find “Playback speed” and set it to 0.96.
• Click “Save.”
• Optional: Under “Audio,” you may or may not want to turn on “Enable time stretching.” If it’s turned on (the default, I think) the audio will be played at its normal pitch (but slightly distorted.) If time stretching is off, the audio will sound lower‐pitched than normal. 
• You may have to restart the program after changing options.
If you’re using mplayer:
• Add the option ‘-speed 0.959’ to the command line.
• Optional: If you want to enable time‐stretching (which is off by default), add the option ‘-af scaletempo’.
If you’re using some other program to play the DVD: please post here if you know how to change the playback speed. Or if you don’t know how, post here and maybe somebody can help you figure it out.
 I’m not sure, but I would guess that the audio for the PAL DVDs has simply been sped up, so that when played normally, it’s higher‐pitched than the NTSC version. But if you’re accustomed to watching the movie at PAL speed, you might prefer it that way. It’s up to you.