Flat, predictable, and predictable.
Laura, I think you need to read this. You don't seem to have any knowledge of comedic timing or context, but have been convinced that you do. In addition, the fact that you have more of these on YouTube isn't a good sign and makes me think that you're nothing more than a modern-day carpetbagger. However, I am going to be fair...
Graphics: This is one of the two merits this has. You have nice backgrounds, and the animation is excellent. However, if there's something I learned: it takes more than great animation to make a great cartoon.
Audio: The music was good, and it fit the situation. However, the voice acting sounded labored and I think that Dexter never saw a cartoon from animation's golden age (1927-1953). Plus, screaming has been done to death. Therefore, I suggest that you watch those golden age cartoons to see how Mel Blanc, Jack Mercer, etc. did it.
Content: I may be a fan of game spoofs, but the ammount of derivative in yours is ridiculous. The aforementioned screaming, the growing up montage, house on fire, it all felt uninspired. This is exacerbated by the fact that they can be seen from a nautical mile. Look, I understand what you're trying to do, but you're not doing a very good job at it. As said before, go watch those aforementioned cartoons because there's a lot more you can learn from them than Legendary Frog, the Zirbes bros., Kirbopher, or Sirkowski. Either that or team up with someone who can do something funny such as Wooden Sneakers, Catoblepas, PeixeAquatico, or Golfinho.
The Good:
-Great animation
-Fitting music
The Bad:
-Uninspired
-Unfunny
-Bad voice acting
Overall: I have no right to give you a zero, but felt that the lack of caustic criticism was sorely needed. Here's a five out of ten and you would be better off if you let the YouTube thing go. (2.5/5)