Display a segment list:
Editable fields Title, Start, End
Can mark as "cut" or "active"
Can remove segment
Segment display on timeline could incorporate some of the items from the segment list.
Segment start and end points have "handles" to easily drag them to the desired position.
What I personally don't like so much about the proposed design: It is kind of "without focus" in means of providing one single page just showing kind of everything.
The segment list is quite useful, but what exactly will a user do with it? Likely, he uses the segment list for fine-tuning when generating the video segments. When not working on video segment generation, however, I don't see value in having segment list being displayed. Why is it displayed all the time? Will a average user jump between editing metadata and creating segments so often that this justifies both information being displayed the same time? The same holds for the track list.
The proposed design suggests that there are actually three main views below the video editor: The "embedded" event details view, the track list view and the segment list view. In this context, the tabs of the event details view are somewhat suspect: I would expect the tab to change the complete view (all three main videos).
Where would we put new features of the video editor inside this proposed design? Think of thumbnail selection, thumbnail upload, hiding of individual tracks, swapping tracks (e.g. position presenter and presentation), ...
Of course, again a matter of personal preferences, but if I understood correctly, the proposed design will be "appended" at the bottom of the current video editor requiring the user to scroll down. Hmm... single-page web applications try hard to move the user experience of web applications to a level users are used from "real" applications. Scrolling seems a step back in the direction of "web sites". Seen from that point of view, I personally would prefer open a modal using a button over scrolling around in a page.
Anyway: Please don't get those comments wrong: Happy to see someone taking care of improving the video editor and looking forward to it!!!