Add more labels/attributes to already published videos

[Woo Kim]

I have several annotated videos which took hours, and now I have a need to add more attributes.
Is there a way to add more attributes without losing the previous annotations?
Or similarly, is there a way to load videos with annotations from an output file?

[mannymengs]

I'm in a similar situation. Is the only option to reload the videos with the new labels, causing all progress to be lost?