Recently I took about an hour worth of video on my camcorder. It's one of those digital cams that has the mini tapes in it, and I'm always stuck trying to figure out the best way to get it off there and onto some format that we can watch regularly. (One enterprising friend said to never bother, just plug the camera back into the tv whenever you want to watch).
It just so happens that the wife's Linux laptop has a Firewire port, and after a little wrangling I found some software (Kino) that would, in fact, capture the video nicely.
I get everything wired up and it starts running. The whole setup is on the couch next to me as I work on my own laptop. It dawns on me that while the laptop has about 3 hours of battery life, the camcorder does not usually do a full hour, so I go plug the camcorder in to wall power.
The video is 57 minutes long, and it transfers in real time.
At 54 minutes, the laptop shut itself down, out of battery. I'd apparently not realized that while doing the firewire/video thing, battery would be eaten at a much greater rate. Dangit. No idea what it did to the actual file it had been building for the last hour, as I gave up and went to bed.
Moral of the story, don't guess, just plug everything in.