this, but not this
There are courses where academic preparation is useful, i.e. CCR, trimix, etc. where establish standards exist. Sidemount is not one of those areas. I recommend that you go into the course with an open mind and absorb as much as you possibly can. Mike and the rest of the team at @Dive Right In Scuba are awesome.
Now, as with any course, you should come OUT of it with all sorts of skepticism that you need to validate through your own experiences because none of us are infallible and with a course like sidemount, there is no establish standard. Your instructors job is to give you the tools to develop your own experiences and adapt as necessary, especially with something as subjective as sidemount.
Why I recommend not watching Steve's materials before the course is because I don't know which school that your instructor subscribes to. If you go in with preconceived notions from Steve's course then you may be sadly disappointed if they teach with a different fundamental set of sidemount techniques. It does not make either one more right than the other, just different and you need to establish that for yourself AFTER you are done.
I respectfully disagree. There are many ways of doing things with different tradeoffs. A student should listen to their instructor and try their way, but know that there may be other options to try. They at least show up with somethings at least partially configured. They will also understand more of what their instructor is telling them.