In the Training Level, find the letters and spell "FLIK".  Each time you do this, you will gain an extra life.  Then, just return to the Regular Game.

Hidden Training Level

Begin playing the Training Level and complete all of Mr. Soil's objectives.  Then, bounce on each of the spiders, killing them, and you will gain in extra level.

Bonus FMV Sequences

Unlock the Hidden Training Level and complete it.