an open source service gets bought/joins an AI company to develop a closed source version of the same service, while leaving the code ot the old clients open.
tablets (especially ones that could be flashed with Linux, i.e. not iPads) are way less common than smartphones, so you get fewer devices to choose from for testing, fewer users who can run it, report bugs, and support the project, and less interest in general.
the creator delayed the launch because he had to write the legalese for the service, and on top of that I think he's waiting for the app stores to approve the app (the service isn't available through a browser).
he mentioned in the past that the videos will be automatically deleted after some period of time, so that should make the storage situation a little bit more manageable.
I use the one from hostux.net, it's quite easy to figure out what "login", "password" and "remember me for 30 days" are in French.