I think u'll find that all the 'turbo gamble to entry' barcrest machines amongst a whole host of other manufacturers have employed this feature.
What it is, is that it say for eg., u have 2 lit up... This allows you to keep turbo gambling till u lose a gamble. If u lose a gamble, then one light is removed. Then u can gamble again if u lose another gamble the last light is removed and u HAVE to exchange to feature. (So, basically, it is a 'gambling life')
However, these are useless really. 3 lights can be very misleading. It makes u think "Ohh i have a guaranteed 3 gambles" but in reality u often lose ur first gamble and get chucked straight back on the trail!
Hope this is clear for u.