Every person is different. I was doing well on exams when I attended lectures, so decided to stick with it because if it ain't broke... Our school also didn't stream lectures or anything like that, and our syllabus could be notoriously spotty in parts, so it was a bit disadvantageous to skip at my school. You could be guaranteed a handful of questions each exam you would miss if you skipped. Some found themselves willing to miss those questions in lieu of having more free time and flexibility in their schedules afforded by skipping. When it comes down to it, lectures aren't the most efficient way to spend time learning and lecturers are not the most efficient educators. But I found the additional time commitment worth it because I felt lectures did really aid my learning.
For schools which stream the lectures, skipping lecture really doesn't hurt as long as you are a disciplined learner. Watching the lectures on 2X speed allows you to more efficiently utilize your time, you don't miss the points, etc. But you can only really pull this off if you can self-motivate yourself to do it every day.
My advice would be to start out with the intention of going to every lecture. That's what almost everyone in my class did, and then over the course of the first month or two the class filtered out. Some people like the structure of going and sitting in a seat for x hours every day in order to learn. Others, either due to children in day care, etc, needed more flexibility in their schedules. You'll find out what works for you. And what works for you for one subject may not for another. You may find you need to be in class every day to do well in biochem/metabolism, but can largely teach yourself physiology, etc. Or vice versa or whatever. Studying in medical school is a constant evolution of trying to figure out what works and what doesn't, and its a very individualized endeavor.