At present, an event captures the DOM either at the time the event occurs, or a delay can be added to capture it after the event occurred, but in some cases we really would like both. Sometimes things change on the page without any clicks or form changes, so it is only when the 'Click' event on an element that has appeared since the last DOM capture that replay will show it, but if the click changes something on the page we would have to wait for another event with DOM Capture to see what the result was, or try to delay the click. Ideally, we would want to see what was clicked and what the result of the click was. This also goes for form changes - if I enter a value and it fails validation, displaying an error message, in Replay I typically have to go to the next replayable event to see the error message being displayed. With DOM Diff, if there are no changes to capture then there shouldn't be any extra message, but if there are changes, capture them and send so that Replay can show the page as it was when the event occurred and then as a next step what it looked like after the event.