Got fed up with typing my password in iTunes Connect every time because the form won't let me copy/paste it. Not sure why Apple is making this more difficult than it has to be.

To circumvent the annoyance you can either disable Javascript or override the onpaste function in the password input field and have it return true instead of false:

document.getElementsByName('theAccountPW')[0].onpaste = function() {
    return true
};

Now you can turn that script in a bookmarklet by prepending it with “javascript:".