Personally, I would add some data to your search engine every time a person makes a new search query by searching that same query on youtube's api (https://developers.google.com/youtube/v3/code_samples/) or by scraping the data. Now that you've got some relevant results, you can sort through those (or all of the URLs you have collected) to give a more refined list of search results. If you want to pay me to get it done, I would be fine with that too.

The problem with buying a premade list (even if there is such a thing) is that it would be a whole lot of trouble to keep it updated.

I agree with the keeping updated part. I am just looking for a starter list of sorts. Thanks for idea regarding calling youtube in the backend, atleast until I have enough data. I will do with it.