Edouard, I saw both videos. The second one is better, but he should have disconnected the battery before doing anything else, specially when putting foil over electrical components. I remove the battery when I wash a motor. 1, to give it a good cleaning outside the vehicle. 2, to wash off the acid from the battery tray and area around the tray. The first time an engine is washed the way we like it, yes its real dirty with caked on grease so you may need a lot of water ( pressure washer) & degreaser to wash it off but from then on a light rinse with some soap & water should keep it clean, Do not use Gunk engine cleaner or another product like it on newer cars & trucks !! it gets into the sensors and you will have big problems with the engine bay electrical systems. In my newer daily drivers I just wipe down the engine bay with a rag wet with soapy water, I put a little Dawn dishwashing liquid in a pail of warm water squeeze out the rag and start wiping.. In the old Buicks I use Simple Green instead of Dawn. I'm not a fan of a lot of water in the engine bay or on the car, water creates rust ! So I wipe down my Buicks instead of washing them. But if I do get caught in the rain "Oh Well can't stop mother nature" life goes on.... Tony