Unlike most of these people, I will actually explain what you are doing =P
You are changing the assembly code. You are overwriting the jump that (i guess?) checks something about your characters speed. Overwriting this jump will cause it to always execute the code below it (but it will also execute the junk code that you are overwriting it with). One way to fix this is to edit the value stored in the register that the jump uses for its check [pure speculation as I do not know how this jump works, nor play wow anymore].
For more information on stuff like this, check out the memory editing section. HOWEVER, I do not recommend that you make any sort of post unless you have done an extensive google search, along with a search of the forums, in order to satisfy the higher intellect requirement of the section.