If your presentation relies heavily on technology, have a backup plan. Each piece or type of technology you use ups the chance of something which could go wrong. PowerPoint, check. Video, check. Sound, check check. World Wide Web connectivity, oooh, check check check.
I felt sorry for the presenter. In that oh-yes-I've-been-there sympathy way.
Always have a backup. Burn a cd or dvd. Thumb/flash/usb or otherwise portable drive. External hard drive. Just don't rely on your entire multimedia presentation being available without a plan B.