Well, while you can mess around in the tablet to do the move, it usually only allows moving one at a time, and that can take a while. Especially if the files are large.
Another way to do it is to connect the tablet to a computer via USB cord. Then move the movies over to a folder on the computer. Organize them the way you want, rename, etc. and then copy them back over to the SD card instead of the device.
I say move to the computer, because that will take them off the tablet itself completely, but only copy over to the card, because that will give you a backup on the computer, should anything go wrong with the card, the tablet, it get broke, stolen, go missing, etc. I would suggest you do that with all your personal info on the...