Here is a bug report.
QuadCam 2.0 is sometimes unstable, when you view animation mode.
If QuadCam crush and you can’t launch QuadCam again, please turn off and restart iPhone please.
This bug will be fixed in next update.
I’m very sorry about your inconvenience. :-(
Next update will out around beginning to middle of January, its depends on apple’s review team, but actually new version is almost ready. QuadCam 2.1 supports this stability bug fix and in-app twitter post.
31th DEC 2009
This bug is fixed.