Have you considered keeping them on YouTube but unlisted, so that they don’t show up on your profile nor in youtube searches?
Otherwise, you could create a Google Photos album, but either quality suffers, or the videos will take a lot of space.
All the other options I could suggest either call for a recurrent payment, but trust me, it gets tedious after a while (ie. VPS with Peertube or similar), or call for losing quality by a lot (ie. Whatsapp or Telegram channels/groups), or quickly become unpractical (ie. Mega, Dropbox…)
There are plenty of choices, and if you’re 100% sure you’re fine with recurring payments and having to constantly mantain a system/keep it updated and secure, then go ahead and make a VPS, but if you’d rather have it be convenient, look into additional YouTube settings or common alternatives like Vimeo.