phrase usage - Difference between "speed up something" and "speed something up"

Both seem to be in common usage, but is there a nuanced difference about when one is more appropriate than the other? Thanks.

Answer

They're both forms of the same thing, a verb-particle idiom sometimes called a "phrasal verb":

  I sped the video up.  

  I sped up the video.

But if the direct object is an unstressed personal pronoun, up has to come at the end:

  I sped it up.  
 *I sped up it.　(ungrammatical)

And if the direct object is very long, put up first:

 ?I sped the new program for rendering alpha and beta particles up.  (awkward) 
  I sped up the new program for rendering alpha and beta particles.

Otherwise it's difficult to understand.