Im getting the same problem in Resolume 2.2,
White previews, and sometimes no preview what so ever - it will look like theres no clip there at all when there is !
This seems to happen on decks made mainly of Cinepak AVIs and MPEGs, my SWFs seem to preview ok.
Like everyone else said - this is a real pain in the ass !
Will attempt to fix and post any findings back here.
My hardware spec:
Operating System: Win XP Home
Processor: 2.81 ghz P4
Videocard: NVidia GeForce 6600 GT
Files type: .avi .mpg
Codec: cinepak, mpeg
James // Meek VJ Crew
Screen shot below -