It might be more productive if you find a forum supporting the mpeg live system (whatever that is (url?)) and ask them "can I write a script which outputs a simple status string based on 1. Freezed Picture, 2. Black Picture ...?
If you get a reasonable answer, then you should be able to write a plugin for Nagios. You haven't said whether it runs on Linux, Unix, Windows or something else?
Can the system you're talking about support SNMP? If so you might be able to use check_snmp to get some simple (or even not so simple) status information from it.