When you watch videos from the video folder on the iphone, does it use data?

I can only use a little data and i'm going on a vacation… I have downloaded videos and i want to watch them on the drive up to the place. When i tried it had a loading circle by the 3g and i didn't want to watch because it looked like i was using data… Am i?

If you hv already downloaded the videos it won't use data aftrwards…

Depends. If you are playing a video which is already been downloaded then you won't be charged for data usages but if you stream a video online, you will be charged for data usages