I've never found a tool on the ipad to convert it, but you can send it by message, youtube, email directly.
The easiest is of course youtube.
Setting up an account, upload to youtube, then send the link by email to your friend/relative/whatever.
Other alternatives, are dropbox,box,twitter. Again, providing links to the other party. Uploading them is fine, but of course windows computers will need quicktime, you can get this at: http://www.apple.com/quicktime/download/
It's a very simple install.