Easiest way to deal with this is to self-host the videos. Most people over-estimate how popular their websites are, and for the ones who don't, getting a dedicated instance with unmetered bandwidth is trivial to get and setup for video-hosting.
In the past when video was a novelty and no one had any real expectation of performance or quality, it didn’t matter much because expectations were low.
But so much work has been done since on reliability/performance/network efficiency and very few products can provide that. Without that work, people will think your player is broken, you will waste mobile traffic, etc. Even Reddit can’t get it right and they are a top 10 website.
Plus YouTube handles all re-encoding and adjust the quality based on the speed and device.
It is possible to do it with open-source components, but it requires a server farm and just not feasible using single cheap private server or VPS.
Now if only browsers would implement native HLS and/or DASH support then every site could have this without having to package a bunch of JS with different quirks of reach site.
Of course, it is not really in Google's interest to help YouTube competitors so this is unlikely to happen for Chrome.
For most videos, this would be a copyright violation. i.e. there are now two laws which prevent reasonable technological solutions, making it harder for most people to host and produce content - favoring the already heavily advantaged big companies.
The solution to bad law is not to ignore it, it's to follow it to the letter, every time. Only then will people sit up take notice, and weigh the tradeoffs. In particular, we've let industry run away with far too much of the public's right to do things.