Steps to reproduce (can be seen on H5P.org):
Go to editor
Select Interactive Video
Add an mp4 video
You will get an error message regarding undefined interactions.
We'll fix it in the next release.
This seems to fix the initial problem, but I get "You must choose an H5P content type or upload an H5P file." when trying to create an IV without going to the "interactions" tab in Drupal.
My bad, it is working very well, good job!
Make sure to answer the thread on H5P.org