The videos on http://iphone.akamai.com/ delete the video element when it posts an 'ended' event. If you scrub to the end and the event is fired and the element is deleted while the mouse is down in the controller thumb, mouse clicks stop working on elements in the page and occasionally we crash in vent handling code in the media control elements, with a deleted m_mediaElement. The problem is that the slider thumb "captures" all mouse events from mouseDown to mouseUp so it continue to get mouse events even when the mouse is moved outside of the thumb. This is done by putting EventHandler into a mode where it sends all mouse events to the thumb regardless of the actual mouse position. The mode is set on mouseDown and cleared on mouseUp but if the controller is deleted while in the this mode, the mouseUp is never sent and EventHandler continues to try to send events to the non-existent node.
Created attachment 32485 [details] Proposed patch
Comment on attachment 32485 [details] Proposed patch looks good!
http://trac.webkit.org/changeset/45662