The guy was just kidding around, so I don't think it's pathetic or insecure. If you read the description of the video, he makes it sound like a joke. Regarding the World's Strongest Man competion:
"The guy who runs it hinted that I might be a little too strong and it would be unfair to the other competitors. So I just won't lift any weights for the next year to level the playing field."
The comments are pretty bad though. Youtube is interesting in that it's one place you can go to find out the thoughts of the dumbest people alive.