What about running a cron job that grabs
\server\c$\Program Files\VERITAS\Backup Exec\NT\Data\BEX*.txt
and then does a
for d in
find /tmp/BEX*.txt -mtime -1
cat $d|grep "Job completion status"
Of course.... you would then need to write a custom plugin to return result back to nagios. That is on my todo list.