At Vimeo we use Varnish to cache our player traffic. It has worked out great for us. Varnish at this point has no built in module to sort querystrings. Say I have two of these:
Obviously we want to treat the above one and the same:
We evaluated a few vmods. We were not happy with their performance/stability. So I wrote boltsort that is 2 times faster than existing implementations and has been running nice and stable.