What's "never mind" mean?

Is there a difference between 'meanwhile' and 'while'?

They both can mean two things are happening at the same time. However, the difference is that "meanwhile" is an adverb that usually starts a sentence and has a comma after it. Whereas in this context, "while" would be used as a conjunction. "While" also has a couple of other meanings, such as a period of time, during a time or action, or as a contrasting point. Ex: I was watching a show while Jen was making dinner. Ex: I was watching a show. Meanwhile, Jen was making dinner. Ex: It took her a while to arrive. => period of time

What's "never mind" mean?

"Never mind" is used to tell someone to not pay attention or mind something. In this video, the speaker asks George where he's been, then tells George to not mind his question ("never mind that") and moves onto a topic he finds more important. Essentially, you are asking the listener to disregard whatever you just said previously. Ex: I want to get a salad for lunch. Never mind, I'll get a burger and fries. Ex: Do you want to go to the gym together today? Never mind, I'll go next time.

What does "who" mean here?

"Who" here refers to the previously mentioned "cat". You can think of this sentence as, "I think you should name your cat Michael."

Europe and America were raided by infamous pirates like Barbary or Caribbean pirates. Nevertheless, pirates are a popular source in literature and media. Why is that?

That's a good observation! The origins of the Western fascination with pirates is quite interesting. Around the time that newspapers became popular, pirates were very active around Europe. Since the 18th century, they have been some of the most idealized, romanticized figures in history. Although they were reviled as outlaws and criminals, there was also a fascination surrounding them because they seemed adventurous, free, and sometimes even heroic. The representation of pirates in famous American movies like Pirates of the Caribbean has boosted their popularity and allowed them to become icons in popular media.

Do native speakers use this expression a lot?

This expression is sometimes used, but it is not very common. The reason it is not common is because there are not many situations where an expression like this needs to be used. This expression can only be used when the speaker thinks the person they are talking to is not being honest, and the speaker wants to confront them about it.