You have to press spacebar repeteadly to gain altitude. That is, a jump will take you as high as usual, but if you jump again before touching ground, you'll get higher, and so on.
I found out also that spinach was needed,but I go to Plexus to relax and watch others..It is a great place..I hope they do another one but some what different if it is possible...
Towards the end of the test, someone in Plexus had the problem of not being able to repeatedly jump; a single spinach later they were fine. So I don't think it's fixed yet....