Okay, I'll be the bad guy. I'll give you my observations and please tell me where I'm incorrect.
#1 I see a diver descending without his buddy @2 minutes what I believe is his buddy is below him, turns and waves to camera diver to come closer which he ignores. By 2:15 he's continued ignoring his buddy and dropped at least 25 feet below him and still dropping. By 2:50 you can see his buddy is easily 60 feet above him.
#2 I can see a good current running along the wall, it's running along and diagonally down the wall, doesn't appear to me to a big deal. @3:30-4:15 you've got a buddy team actually finning down to descend and keep their heads into the current, it takes them at least 45 seconds to descend the distance the camera diver did in 10 seconds. They obviously are taking it slow and conservative as you should when diving, are not dropping down like a rock, are aware of their surroundings have situational awareness. At 4:26 you get a good shot of the two divers, the wall and the bubbles and you can see it's a good current running laterraly along the face. The camera diver@ 4:43 for the first time realizes he needs to put air in his BCD to stop his rapid descent, he's feeling the pull of the current and the results of his rock shot drop descent and starting to let conditions over-whelm him.
#3 From then on the camera diver is panicking and over-reacting to the current, he's been very aggressive in his descent, very unaware of the current and totally ignored staying with his buddy, he is now feeling the pull of the current and hasn't adjusted and starts panicking. From there on he's panicked. @5:00 minutes his buddy appears, obviously the current was totally manageable if this is the buddy from the descent, as the camera diver had 2 and 1/2 minutes of separations and the buddy easily comes to him. From then on the camera diver is panicked and over breathing his reg and does what inexperienced divers who panic do which is head to the surface like a balloon.
* I'm not condemning the camera diver. These are my observations based on what I see in the video.
Based only on what I could see from the video -
1) Current was not deadly in any way.
2) Camera diver would greatly benefit from some training on descending properly
3) Camera diver would benefit and be safer from developing better situational awareness
4) Camera diver needs to understand how important it is to stay with buddy during descent and on dive
5) Buddy diver needs to understand the same thing
6) It's quite possible that the buddy couldn't have grabbed the camera diver on his ascent, but if it was possible, he should have grabbed him and done everything possible to hold him at a safe depth, calm him down and do a slow safe ascent to safety stop. But like I said, hard to tell from the video if it was possible.
7) Buddy needs more information about the issues of in water recompression and the better choice would have been to put the camera diver on 100% oxygen and monitor for DCS symptoms
Glad the camera diver survived his panicked rapid ascent with no heath issues. Being a mom and that was your child, that has got to be horrifying to watch (the panicking part) and heart goes out to you.