Well while I do not think Cricket or its provisioning on a VZW phone is the issue, I keep leaning back towards the encoding process involved bc keep in mind these movies in mpeg and avi that you DL'ed are for a full size PC screen in 800*600 or even 1024*768 and not for 320*240. And even if that isnt the issue (video compression) then still the audio CoDec could be it. Use something like
GSpot to find out all the info about the file you are trying to play.