I did a partition install of yosemite this morning. When I tried to access FCP 7 in the Mountain Lion partition, I got the message “check with developer to make sure FCP works with this version of OSX. I became worried. I did a fresh install on the yosemite partition and it installed and opens as normal, WHEW. Opened an old project and it seems to be fine. I haven’t checked all my normal plugins yet, but to confirm, FCP 7 DOES WORK. You may need a fresh install, though.