I have played about 10 songs and not one single song did arrows match up.

IT'S SYNCED TO A CPU OF COURSE IT'S NOT GONNA SYNC CORRECTLY

because they have the time to sync every single video on youtube

Sometimes it's actually synced, it just depends on what the game considers a beat and how fast the songs are.

The charts are not written by people, they are generated by a computer. If you're expecting guitar hero etc quality charts then they would have to allow players to make charts for videos.