There are two problems:
1. The aspect ratio of the tool does not match the transcoded video, resulting in black bars (visible if you skip to 0m10s). This is not just one video, but on every page of this exposition the topmost video has this problem.
2. The aspect ratio of these particular video tools (unlike other video tools) is locked, which means we cannot adjust the height to get rid of the black bars (changing height immediately changes width as well).
Perhaps, as a pragmatic solution for now, can you remove the lock on the aspect ratio of the videos within this exposition ?