Convert bkg to dds Online: bkg2dds

You can use Tom's Editor to easily convert images from
Movie Maker Background .BKG to Direct Show Surface .DDS.
Tom's Editor is a free, online image manipulation and converter program.

Go to Tom's Editor

BKG

Movie Maker Background is an image format with extension BKG.

DDS

DDS are files invented by Microsoft to be used in games, mostly as textures. Images can be compressed to save space but the compression methods defined by DDS are all very fast in terms of coding and decoding.