I'm surprised at those figures - your most popular video has 100k views, and 4 comments - I wonder if you used any tricks to get those viewers, because that would suggest to inexperienced me, that you're not connecting to your viewers?
Looking for comparison, two of my films that have 60k views, both have 7 pages of comments. 2 @20k views have 3 pages of comments... Maybe as a general rule, 10k viewers = a page of comments?
Maybe you used some clever method to get people to click on your video, but they left fairly quickly afterwards?