I've noticed in some streams of this game the flashing lights from the tetris are removed. How do they do this? Is it some secret mode in the game, or is it something done with OBS, or AmaRec.

NES Tetris runs at 60fps. If the runner is recording at 30fps, it's possible for the flash not to be capture (since the flash happens at frames skipped in the recording). Happens all the time on Tetris streams.

Thanks again for the information! It is greatly appreciated!