If you have a camera adaptor for your iPad, you can use an SD card to transfer movies and other media onto your iPad, without having to sync using iTunes.
From your computer, just create the folder /DCIM/100VIDEO on your SD card and put the movies that you want to transfer into this folder. Then, when you plug the SD card into your iPad, you can import the movies into Photos and watch them from there (instead of watching them from the Videos app). Maybe set up an album in Photos that holds your full length movies, so that you can easily access them in future.
Just make sure that the movie is in a format the iPads can play - you may need to covert it first. That's a topic for another article!
PS. You may find the above trick works with some USB sticks as well. Give it a try!