Before you do anything, go into pose mode select the “null foot” bone and remove the constraint (press the “X” in the constraint panel) then rearrange all the bones back into position (in 2.4 you can select them all and press ALT-G but in 2.37 that doesn’t seem to work on this armature)
You haven’t set the IK constraints as the tutorial shows. See this image for example:
Select the “foot” bone, go to the constraint panel and fill it in as shown above. The “foot” bone will jump to the “foot IK” bone.
Then select the “toes” bone and add a constraint on it targeting “toe IK”.
Having said all that, it’s all about to change. Personally I think it’s still worth understanding this because even the new system uses IK, it just has a few different ways of applying it. But if you don’t understand what IK is then even the new system will have you stumped for a while. But I wouldn’t complete that whole tutorial - just play with the basic setup but ignore the advanced one.
Gabio has begun the updated armature docs here: