This level requires you to jump through holes in the middle of platforms above your head. You need to jump through these otherwise you will not be able to beat the level. (Actually you can beat the level without jumping through these holes, but it is very difficult to do 5 times in a row).
The 4th hole in this level is difficult, however, it requires you to curve around the left side of the platform over empty space, so you need to time your inputs very carefully.
To get the bonus, on the final bar, you must go through the left hole which is hanging above the void so be careful when collecting. This is only hard due to the fact you need to do this twice.