> If we multiply that by 30x for video (a fair assumption for models like minimax H3, which take that much longer to make video)

It takes about 7 minutes for my RTX 5090 to generate a 15 second video with MiniMax H3. At 600 watts, that's 252,000 watt-seconds, or 0.07 kilowatt-hours.

My electricity is 18 cents/kWh, so $0.0126. Just a little over a penny.