I have seen a mouse scurrying about in that area in the past so I guess that is what attracted the owl.
Now I can see how much the camera covers I intend to increase the number of bird feeders in that area. The wi-fi cameras are connected to their own base station which is also a recorder. Real time coverage can be watched on a monitor and any movement is automatically recorded. Unfortunately it didn't seem to detect the moment the owl flew away.
Copying the saved file to a USB stick is easy. Unfortunately the version of .avi used is unrecognised by all but one of the Mac video player apps I have. That app doesn't have the facility to convert videos to another format. In the end I have to use Quick Time Player to screen record while Total Video Player played the .avi! Even the Mac version of HandBrake didn't recognise that video format.
P.S. Finally found a new version of HandBrake which does the job.