You can cat .mpg files together, but you should not. ".mpg" is supposed to refer to an MPEG Program Stream, which does in fact have a header. You can cat Transp

You can cat .mpg files together, but you should not. ".mpg" is supposed to refer to an MPEG Program Stream, which does in fact have a header. You can cat Transport Streams, but these are supposed to have the ".ts" extension. You sometimes get transports streams named ".mpg", which complicates everything.