Since it is "page rank" I always believe it needs to be because of the text in your video... example if your video is about dogs and someone comments "that's the cutest DOG" I think this helps your rank ( the bigger the comment the better and when you reply back make sure you add some key words in your reply and use up all the characters allotted)....also I think if you use some good text in the info area of your video... not necessarily a huge amount of text only something that includes the title of your video as well as a few of the keywords your using...

I get ranked very fast using this technique.... Do you want to know why it is important to have a good pagerank on your video??? I will tell you... it puts you up higher in the google search as well as the video (regular) search in youtube...

okay I just told some very big secrets here so I hope they help you. Thanx are in order and heck I might tell you a few other tricks down the road