Isn't it third party from the tv vendor? I think that was the implied context. Although If you consider yourself as the vendor who built the device (did you really?) that would be first-party I guess.
If I do banking on my TV via an HTPC I've hooked up, e.g. lots of setups that have a TV as an external monitor, I don't want those being screenshot. TVs are used for a lot more than strictly TV.