allow moving videos on the timeline (set video date)
when moving a video on the timeline there are some things to consider:
- you should be able to move a video with its annotations (although the annotations are not connected to the timeline) to move it to a proper historic date
- if multiple videos are added overlapping and are post-annotated, how can we achieve this without messing everything up?
- should you also be able to move a video without annotations to allow for corrections?