How do you find these? You search alternative video players or is there some site where you enter a youtube url and it gives you alternatives?
It is called individious, there are many hosts you can choose from. In any instance, a youtube link you paste in the search bar gives you that video in individious. If a certain video is not working, you can use “Switch Individious Instance” to quickly jump to another.
Personally I use a browser extension called LibRedirect.