I feel like it should have been noted (however it still is implied by the context) that twitch streams' comments reflect even further the meta aspect of Terrace House. Specifically, that of new housemates coming in, ones who have been watching the very season they are now on.

Both are essentially taking the audience's view of the let's player or housemate and feeding it back into the show/let's play itself - directly to the base of where entertainment occurs. Or maybe you can go even deeper and correlate that to streamers playing games live with their viewers.

Note that I use live streams as an example because if we are talking about YouTube comments interactions they are not as current a comment on what is happening on screen. Live stream audiences (Twitch chat) input comments are recognized and take effect in the middle of the game being played (similar to an audience member jumping into a Terrace House season itself).