I have done posts about commenting in the past and one of the best things I have found is to ask a question in your comments. Even if it is just clarification of a point or asking what the original poster thinks about a similar topic, it shows that you read (or watched) and were engaged. It always drives me crazy when people leave the short little comments unless you know the person and have an established relationship with them. There are some people that I have been following and they have been following me for quite some time. I don't really mind when they occasionally leave a short comment.