Hey all, quick question about the iPod Video (5th Gen) - Is there a specific format of video that would save me some battery life? I'm going on an 18-hour trip to San Antonio, and I'd really like to be able to watch movies and listen to music as long as possible. I bought the Duracell instant battery USB charger, but I don't know how much it will help. Basically, I need as much use out of this thing as is possible. Any ideas from past experience?