There is in my opinion no way an instructor can provide adequate feedback to a student who is studying from their videos online. By the time they could do it the student probably has already ingrained bad habits. Take for instance I was teaching a student just the other day. We were working on a handgun disarm and I noticed as he was practicing it on me that he twice flashed his own bicep with the muzzle while doing the disarm. Done correctly this would not happen. I immediately told him what he was doing. I also showed to him what he was doing and how to correct it. We proceeded to train and he did not make that mistake again. No online sifu/instructor is going to be able to provide that kind of feedback even if they were doing the online training in real time. How can I say that? Well if you were not training with the person and looking at what he was doing from another angle you more than likely would have missed his mistake and he would have ingrained a very bad habit. I have mentioned before that I have had quite a few people come in and train after having learned a submission move. Unfortunately most of the time they learned it superficially with no depth or incorrectly. I then had to show them their mistake or where the holes in it are or how easily it is countered because of this mistake they have ingrained. Now I am not saying that you cannot learn some stuff provided you have a good base in the system you are working within and a real instructor that you are training with who can correct you. What I am saying is that if this is your choice in learning the Martial Sciences then be prepared for lots of bad habits, poor skills and probably a craptastic experience. It is much better to instead choose a real instructor, travel to them and or seminars and learn slowly with lots of corrections and hands on experience along the way! Hope that helps!