4 coins eh? (I'm surprised you beat Extra 5 perfectly before you beat Extra 4 perfectly...)
Well, I think the coins you are missing (and the one I always forget) are 4 coins near the right-hand side of the light section (the one without the spotlight). Ummmmm to get there, I think you go to the top of that chamber, than go down a drop opposite the way the arrow tells you to go. After a long drop, The 4 coins are in a small room. After getting them, you go down another drop, and find yourself on the VERY right side of the light area. Hope that helped..... (I am doing this from memory. Remember this. It may be confusing, and I am sorry if it is.)
Any other questions about the game? I know way too much about it.....
And good job getting 100 on Extra 5. I generally die about 10-20 times getting 100 on that level even now.... although about 70-80% of them are intentional (i.e., after missing a red coin or 2 on the skiing part, I don't even bother hopping the next gap. For me, it's either 100 or nothing.)
*My real signature went on strike, said something about "unfair working conditions". So, this is a temporary replacement sig, until I can work things out with the real sig.