How can I pause ALL videos (html5) at once?

There's no real need for jQuery, the ES6 way (that should work in most modern browsers...)

For all <video> tags:

document.querySelectorAll('video').forEach(vid => vid.pause());

or in your case (looking for the .vid class):

document.querySelectorAll('.vid').forEach(vid => vid.pause());

Try

$('.vid').each(function() {
    $(this).get(0).pause();
});