I have to say I love this question! I don't think you're one of our beta testers so that will guide my response.
NextRating is not integrated with FF and does not analyze a tracklog as part of its role in the debrief. The debrief features of NextRatiing are intended in part to help the CFI's debrief succeed in its thoroughness and in its learning impact and retention by the pilot.
If I re-phrase your question to be "How does the CFI's debrief session with the pilot in training compare with just having the pilot go use CloudAhoy?" then for me the answer is pretty clear. I often use the tracklog debrief feature in FF on the web, because I think it's pretty cool. It has not come close to achieving the level of learning that a CFI provides. For example, the CFI's debrief can walk me through how I used throttle and flight controls in the pattern and final approach. He can point out what I did or didn't do with the rudder when I started the turn to final, saw I was low and added power. He can point out what I had done that caused me to be low. He can remind me how stalls happen on the base to final turn. The EFB debrief tools simply cannot do that. The example I just gave was a real case, and the tracklog debrief in FF scored that pattern and approach as a 95, implying I had no room for improvement.
My thinking is we need more CFIs doing more good debriefs, and we need the pilots in training to be reviewing those insights again at home, doing some chair flying or whatever. We do not want CFIs heading toward letting CloudAhoy automate that part of the job.
Regarding your suggestion about needing videos. Totally agree, that needs to come. For now the app is still being formulated, first by the developers and now also by the beta testers.
I hope you'll consider signing up and giving us more good input.