You can't pick an earlier frame because you always only have the current screen in the videao memory.
Two ways i would try (depending on your project)
1. save the last X frames (Snapshot canvas) - but this might take too long?!
2. save the positiones/attributes of each object into an array. To restore the X'th frame you have to set all positions/attributes of all object (can become tricky if you have recreate objects they where deleted meanwhile )
There are other methods also but this can be implemeted quick...