When the VncServer is not availlable or the Vnc Server can't acces to a display session, the video file will not be generated.
Then, the

public boolean tearDown(AbstractBuild build, BuildListener listener)

methode will return

false

and the Build is marked as ended with FAILURE.
It should be possible to configure the plugin to let the Build marked as succed, even if video capture as failed.
Regards, Éric

ERROR: File /var/lib/jenkins/jobs/edu.nightly.EZ.step1.AosBuild/builds/153914/archive/edu.nightly.EZ.step1.AosBuild_153914.flv doesn't exist. 
Feature "Record VNC session" failed!
Finished: FAILURE