I finall got around to watching both parts and - as expected - enjoyed it very much. It's always nice to hear someone who knows about this stuff put into words what you yourself can't (especially not in english).
I have a couple of thoughts and hope it is ok that I post them here instead of dividing them between the two threads.
Now, I love the Beach Boys as a live act during these years, as I mentioned before. I always thought they were much better as a live band than people give them credit for. How they were able to play these songs with just four instruments and nail those harmonies at the same time is impressive. Especially considering that none of them was a pro on his instrument. Carl came probably the closest and he wasn't even of full age!
I have my problems with the album though. It is to be expected for live recordings to be cleaned up, maybe even partially re-recorded in the studio, as Adam points out in the video. That's ok. My two biggest problems though are the use of the studio-recordings backing tracks on "Fun, Fun, Fun" and "I get around". This really takes out some of the excitement because of the definite change in sound compared to the not-as-polished backing tracks on the rest of the album. Second, the sound on the whole is what I could only describe as "too thin" without being able to explain what I mean with that. But only "Let's go trippin'" sounds really good to my ears. Maybe it is the definite separation between the live music and the studio vocals, I don't know and I really can't even explain what exactly I mean.
On the other hand I don't know if so much of the vocals were re-done in the studio or if closer listening and comparing would show that there's more "live"-vocals than we think. Unfortunately I'm not in the position to check that, because I don't have the ear for that.
My go-to are always the undoctored live recordings of the two Sacramento shows. Sure, there are mistakes and all, but that is what a live show is about: playing your songs without a chance to re-do them. The Chicago '65 shows are great as well with Carl playing his Rickenbacher (at least that's what it sounds like to me). I would also love if there is more footage
like this which then could be used for a new documentary, I hope.
Nayway, their need for Brian is obvious if you compare these shows to the ones with Bruce in Michigan in 1966. The band lacks fire and excitement, just listen to "I get around" (which actually
never sounded as good again live as in '64 imo). This is not to put Bruce down. His job was nearly impossible. He had to learn to play an instrument he never played before in a couple of days and at the same time sing those tough harmonies and most importantly nail them. Other people would have failed lousy.
I also don't know if Dennis didn't contribute some backing vocals during the live shows. You can obviously see him singing along with the guys on stuff like "Surfer Girl" on footage but I don't know f there were mics picking him up or if he was just doing it for the love of it. In the 70s and 80s I believe he did sing on "In my room" while drumming as C-Man or Ian pointed out IIRC.
I love that you talk about Al's contributions. The man gets so overlooked that it's a shame. He certainly was no "star" and not one who stands in the limeight. But his work as part of the group's sound (and I'm not even talking about his success as singer, producer and arranger) is very important as he is one of the guys who lay the foundation for the others to shine. You can actually hear his guitar parts very well during at least one of the Michigan shows, as Carl's guitar was nearly inaudible during the "Surfin' USA" solo on the
Medley that was released on the Endless Harmony soundtrack.
BTW I don't recall seeing that shot of Mike doing "Monster Mash" before. Were there different cover versions of this album? My LP ony has the front and back cover. The latter looking like this:

I probably need to relisten to the "Beach Boys Concert" album and see if anything has changed in my view. Thanks for the reminder and for sharing these videos with us.