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I probably would not use the "Share" feature on an iPad, when trying to share with such an old computer OS (Windows XP).
The better way to do this, is to use a service.
You can send large files (such as videos) using a WEB SERVICE.
This is MUCH better, as it removes the compatibility issue away from the different computer systems (iPad, and Windows XP) and brings them to common ground....the Internet.
The process is simple enough.....you upload your video (from iPad) to the service ( i can tell you which one, if you want?) and then you go on the WinXP computer, and access your upload and download it.
Thats the process, but in practice there is a few more actions.
You coudl also use a CLOUD drive to do basically the same thing. But they do limit the amount of data you can put in any one free account. But you could in theory (as i do) open more than one account, which brings your overall total UP, but limits any single file to the max account size. Make Sense?
If you would like some one-on-one help. we could do a REMOTE SESSIOn?