Re: YouTube - good or bad for aikido?
As Asai Sensei from Germany said to us at our summer seminar. "This is how I do the techniques and in my seminars do them my way" ( I am paraphrasing a bit). " When you practice with your sensei you should do them his way."
I think Youtube is a great resource but it can cause confusion on the mat when students bring a youtube "style" to the dojo.
As well I believe it causes difficulty for newer students in learning basic techniques (kihon) and doing ukemi.
my 2 cents worth