All of it would be relevant, otherwise why would it be told
When I was at school, our lessons were not lectures, and even then on the odd occasion where we were made to copy off the board, I used to try and avoid it as I knew that I was never going to read that again. Rather I used to take time to understand it at that point. If it was too rushed for me to understand then it would have been to rushed for me to copy which was a fault of the teacher for not using the time better, i.e. running through it with us and making the source of the material available to us so we could learn from it in our own time or spend more time on that in class.
By the time we got to 6th form, we were allowed to take pictures of the board
, although I wasn't one of those people because by that time I realised the school powerpoints were dire and the material found online or in the school textbook was far more useful.
At my first uni, things were different. The material was a lot tougher to understand (impossible within the lecture) and find good educational sources online. I did really well in the modules with recorded online lectures and good online notes and not so good in the modules with the backward lecturers, still relying on students to take notes however they could within the lecture.
At my second uni, lectures were ONLY online recordings and classroom based lessons only consisted of seminars. To be honest it doesn't take a genius to work out that this is the more efficient way. Going to a lecture is just pointless, but watching recordings you can pause it and at any point and do whatever you need to do to understand the material, whether rewind it a bit or quickly research that section of the material in between, or if need be, make quality notes at the same time as understanding it. Any questions you need to ask are for the seminar; it's not as if any questions get asked at usual lectures anyway. I wouldn't even call this extremely progressive really, there are just way too many universities stuck in the past.
If you are handed good quality lecture notes then that's good. However if that is all that is required then there is no use of a lecture is there? Although obviously watching/listening to a lecture might suit visual/auditory type learners. Although sometimes the case, a lot of lecturers don't provide quality notes, in which case, a recording would of course help students to re-run either the things they didn't understand at the time or to add to the notes that were missed.