The Legend of Zelda/Emulators
From Red Candle
What is valid?
The answer is, almost anything. NES emulation is very well understood, and very well implemented. Most popular emulators are accurate and acceptable.
It's a common practice when doing speed runs on an emulator to document your emulator and version, and to record with the full window visible, but that's not required for the boards of this game.
Here are some popular options: