If I have a clip open in both Firstlight and Vegas 10, I can't get the changes I make in Firstlight to be reflected in Vegas. If I save the project in Vegas and reload it, I can see the changes. I have the "sync" tab checked and have it the sync button numerous times. I have also tried changing preview resolution in Vegas to see if that would trigger an update. Sometimes it works but most of the time it doesn't. Am I missing something? Should this work?

This is Vegas (and other NLEs also) frame caching, it needs to forget frames it has played. I expect this to improve greatly with Vegas 11.

I havent found this,
I have my project playing on the Vegas timeline with video output from Vegas going to an LCD TV through a Blackmagic card,
I then make adjustments in First Light and see the changes in real time as its playing on the TV.
Its great,
Thank you David and the team at Cineform :)

Try just clicking another spot on the timeline in the same clip

This may be related. A lot of the time, my changes in Firstlight don't even have any effect in Firstlight. In other words, I can make changes on the right panels and nothing changes in the video part of the window. Both the tabs below the window and in the right panels in this case have their "enable" tab checked. Sometimes it works, but more often, they don't seem to communicate. Maybe I just need to reinstall Firstlight.

Edit: I just noticed that this happens mostly if I just load one clip. Then my changes seem to have no effect sometimes. If I load several clips I can bring it back by switching between clips.