Related videos, as far as I know, are a big part of YouTube’s success.
Having a huge library of videos is fine, but there’s always the question – “What to watch next?”.
YouTube algorithm might be a huge accomplishment, but sometimes a viewer wants to watch specific things.
This is why I like the option of filtering results by type.
If I watch a video: Smile (1992 Digital Remaster) – YouTube, YouTube will ask me – would you like to view this or that kind of video?
It looks simple – ask people what they want and just offer them those things.
In practice, though, not that many websites do.