Hi Hugo,
I am sorry for the delayed reply.

Today, we had a demo setup with the latest WordPress/BuddyPress and I am able to replicate the space. It seems there is something forcing the calculated vimeo iframe height(not our css) to be more that what the contents are(this is workign fine with twentytwenty).
I am looking at it. I will have a fix by Monday.

Regards
Brajesh