Thanks for the video.
1. It was tricky to tell if the channels not playing back are audio channels or software instrument channels?
2. Next, when you saved your project in Logic 6, where did you place the audio files used in the project?
3. OK. Another thing, in the Finder go to the folder for the project and look inside the sub-folders for the audio files referenced by the project.
4. Next, open the loop browser and select a loop to play it or turn on the Metronome and hit play. Do you hear ANY audio from Logic? Do you see the level meters on any channel strips? Which ones?
5. Try closing the project and re-opening it in Logic 8.0.2 (just want to check you have the 8.0.2 update installed...) .... Instead of clicking on "skip" for audio files, use the manually or search functions and make sure to find them.
6. In the project folder you should find some backup project files... have you tried opening any of these?
Thanks & good luck :)