Look at an app called PhotoSync. I think it can transfer videos from device to device via WiFi.
You cannot do it with iCloud as there is no way to download the video from iCloud. Your camera roll is backed up in iCloud if you were to restore from a backup, but you can't retrieve them on to another device from iCloud.
You can use DropBox to move a video from one device to another, but it could take a while to upload and depending upon the size of the video, you could max out a free 2GB DropBox account, if that is all that you have in storage space in DropBox.