New project type: Session
This is really touching the software concept, so it's something we need to discuss, maybe also with @florian-jenett.
First, the reason for my suggestion: we again and again have to explain Timelines and the concept behind. On the one hand I think it's okay if there is a small learning curve and it will also become more clear as soon as the Timeline Viewer has some more features and visual elements.
However, things like the circumstance that annotations are linked to the Timeline and not to videos will remain unclear if people do not really engage with the concept (deeply). I recognise that even people of whom I thought that they got it, still get confused. Some things can be solved by improving UI and UX but I also ask myself how much guiding elements will be needed to prevent especially new users from getting confused or messing up things (e.g. moving videos on the timeline without the corresponding annotations).
What I would like to achieve is that you can annotate a video without adding it to a Timeline. To not mess up the underlying concepts of the software, I could imagine, that a "Session" (or "Annotation Session"; not sure about the wording) would allow you to create a timeline "underneath", that has exactly the length of the video that you choose for your Session (OR that is also an open end timeline, but the Session only displays the section with the selected video). So it's still a timeline, but you won't recognise it, you can't add anything else except one video/file. "Opening" a session will always lead you immediately to the post-annotator.
For the more advanced users, we could (later) add the option to merge Sessions into a Timeline. In case you started your work with a Session, added another one, and another one and then recognise that these Session actually already document a (choreographic) process, you could then still bring them together on one Timeline, merge them with another/new timeline.