I’ve heard of a diesel-electric logging truck that uses this concept as well. Use the batteries going up the mountain empty, charge them again going downhill loaded.

I watch long videos on my TV (45 min - 1 hr) and YouTube has the audacity to shove minute+ long ad reels in my face every 15 minuets, claiming “fewer ads for this long video.” Bullshit. I have learned however that if you go to give feedback on the ad and flag it as inappropriate, it skips all the ads in that reel and sends you right back to the video! I can get past unskippable ads in a few seconds this way.