hard to tell from the vid but it does kinda sound like u have gremlins in it. when its rpms are low, that sound is pretty normal i think. whenever i video, especially with my phone, it sounds like that. but when you hit the gas there is a rattle. does anyone else hear it, can you hear it in person more. that sound if i am correct with my listening is piston slap. did you put the motor together and have it bored with a new piston. whats the story? did you use your phone to video?