Hi frankbaku,
If you upload video from anywhere in the /wp-admin it uploads directly to Vimeo skipping the server.
If you upload video from the front-end, the video is first uploaded to the server, then to Vimeo and finally it is deleted from the server.
It is like this because of some limitations and the need to expose the access token in order to use the Javascript only upload. So, we decided not to do that on the front-end because it can be abused and attackers will be able to make unauthorized actions using the access token.
Best,
Darko
