According to that Youtube uses likes/dislikes in its rating alrorithms and enabling them puts your video higher on the search que and thus giving you more views, in your case your video is actually funny so i doubt people would dislike, other than the super uptight ones who cant take a joke
Nowadays, I don't worry about the negatives unless they are really out-pacing the positives. If I believe that somebody is intentionally sabotaging a video, then I will turn off the ratings.
If one can suffer throught the negatives, allowing viewers to give it a thumbs up also winds up allowing them to promote your video if they have such options enabled. In other words, If they like a video, they might also have that auto-publish to their social feeds such as Twitter and Facebook.
Cool dude, thanks for sharing! I always wondered about disabling ratings. I guess YouTube keeps those videos further back in the search results since they don't know what the opinions are on the videos. Or maybe comments/ratings have something to do with the algorithm of search results.