PS3Hax member aldostools has released a nice homebrew tool he is calling: CreatePS3EXTRA
What does it do? To quote:
It scans for the PKG, MP4 and P3T files copied to each game folder or its PS3_UPDATE folder, and store them under a PS3_EXTRA structure. When a game is mounted with multiMAN, there will be 2 BD icons on the XMB: one disc for the game itself and another with PKGs, MP4 and P3T. It should make it easier to install the game patches, DLC, fixes, and related videos.