Q: how to download or transfer a video from ipad mini to computer?

When you attach your ipad to your computer it should show up in the list of devices as a Camera device. Click on the device and subsequent folders and you should eventually see any photos or videos that were in your camera roll.  Just click/copy the ones you want to a folder of your choice on your computer.

There are many ways to do this and doing iTunes way is one old fashioned way that works but requires way too much skill.

Another way is to transfer to cloud drives like Dropbox and then read it off that

The third way is to use applications like ours called Documents.Me wherein you install an agent on the Mac and then all files show up on your iPad and whichever one you need locally just download it to your iPad or iPhone over a wireless connection.

The best thing I've tried is to download iTools their you can add and transfer your musics videos etc. in your computer...