Kaltura doesn’t give you a direct link to their videos when you select Share.

In order to trick H5P into accepting the video, you need to select Download, and then Right-Click on the download icon in order to trick H5P into accepting the video.

Then simply copy/paste that into H5P interactive video location:

It will say Unknown Video but if you go to Step 2 tab to add interactions you should be able to see and play the video.

The video should be set to Unlisted or contact me to make it Public

Public Video:

Unlisted Video: