My idea was something like OddConfection said, having a variable that only goes up (you might need to check if the player vectorY is positive so you don't add negative values to the variable, not sure if speed is negative when going downards).
Imagine it like this player speed is 10, variable starts at 0, you add te speed(10) to the variable, scroll camera to the variable. On next frame camera will be at position 10, that keeps on going until you start falling, Imagine you kept it going until you reached 100 height, if you don't subtract values from that variable it will stay at Height 100, then you can check if distance between playerY and cameraY is greater than X value to check if he died.