Each device uses a unique device number, but the subdevice varies. The Panasonic VCRs use mainly subdevice 0, but also uses subdevices 1 and 5 and maybe others.

Each of those has 256 possible commands. Searching all 768 would take a long time (my MakeHex program together with IrPanels.exe makes that easier. But it's still quite a lot of effort).

Lots of people have looked for Panasonic discretes, so I think you can find them more easily in the discrete forum rather than searching by yourself.