Still almost impossible!
IOS will never be a serious OS until you can do simply things easily!
Setting device to manually manage and drag from windows folder into device does not work. And, doing so deletes everything else that was on the ipad because it was previously synced to another device.
So, you have to add the video into the itunes library, then set to sync the playlist which the video is added to.... but then, the ipad starts 'backup', which is taking forever... can't move files to ipad until it has backed up gigabytes of data to my tiny laptop ssd.
Apple are joke, rant over. . . .