I've been able to use pymavlink.mavutil to read telemetry from a .tlog created by MissionPlanner.

To do this, I create a mavlogfile like this:

mlog = mavutil.mavlink_connection('mylogfile.tlog')

Now I want to read the flight parameters (settings) from the .tlog . The method mavlogfile.param_fetch_all() appears to be designed only to work with a live telemetry link rather than a log. It sends a parameter request command, which obviously has no result when you are linked to a log rather than an actual aircraft.

I know the parameters are in the .tlog... how do I get them out?

m = mlog.recv_match(type='PARAM_VALUE')