It sounds like the tutorial is saying (a video link with a time stamp)
I've just kneaded the dough in my stand mixer, you can also do it by hand if you'd like until it's nice and soft and smooth about five minutes
there are at least 2 possible time ranges: one is
kneading the dough for about five minutes before the dough is nice and soft"
another is
the dough has turned into the soft and smooth state, and then kneading the dough for about five minutes
which time range does "until about" refer to?
Is there need to be a "for" here which is commonly used in "do sth. for five minutes"? So, the original one is rewritten as this
I've just kneaded the dough in my stand mixer, you can also do it by hand if you'd like until it's nice and soft and smooth for about five minutes