タイミングベルト交換！E07Zはココに注意！アクティ・ウオーターポンプ交換！タイミングマークの合わせ方や仕組みをプロが解説！timing belt and water pump replacement 

You should try to do an english translation, I think you would get a large following from America and other english speeking countries. From watching what you show, I think I understand the correct way to tension the timing belt by only using the tensioner spring and turning the engine to get the belt slack on the tensioner side of belt. None of the America RU-vids show this (they put too much tension on the belt. Being a Mechanical engineer, I am guessing that when the engine heats up and expands between the cam and the crankshaft, the belt gets tighter. The tensioner spring gives the correct tension for adjustment before tightening the bolt. Too much tension at operating temperature is bad. Thank you

クランク側の合いマークを半コマずらす理由はなぜですか？