In a number of his videos, they'll use different colours for different speakers. As best as I can see, while also choosing bright colours unlikely to cause problems for people with colour-blindness. It makes such a difference.

Yes, a few people I watch do this and it's so helpful.

I wish more people out the time in, given how the state of AI is going I'm not sure when the auto generated subtitles don't differentiate between different people.