RegexMatchAt(yourstring,"Hi my name is [(\w+)\]\.","i",1) (only works when it's one word, no spaces)
RegexMatchAt(yourstring,"Hi my name is [([\w ]+)\]\.","i",1) (spaces are allowed)
RegexMatchAt(yourstring,"Hi my name is [(.+)\]\.","i",1) (any characters are allowed, must be at least one character)
one of these should do the job, depending on what you need