http://www.youtube.com/watch?v=ei3wfe_k5fg
have a look at andrews video. Notice how the scene changes between between focusing points and he either stopped recording between each time he needs to focus at another subject, or he has cut out the bits whilst he focuses on something else.
I think part of your focusing issue may be because you are using a lens that cannot focus up close as you would like? If that is the case, then take a step back. Record once you have sharper focus, even if the subject doesn't fill the screen, it is a better result.
Anyway the brilliant video linked above will give you an idea of how to go about.
I hope you don't take offence to my criticism. I only mean to help you improve.
Good luck.