I think you know that the rails, themselves do not connect; only the plastic tabs and metal connectors on the underside of the track pieces connect. Attempting to connect the track together like most other manufacturer's track will not work.
With the two track pieces upside down and facing you, slide the plastic tabs on each piece over each other (you are not trying to connect or push the pieces together at this point - just laying them together). Now rotate the two pieces towards you so they are right side up and level. Now tilt the outside ends of each piece (not where they meet) up about at a 10-15 degree angle and push the pieces together. Now tilt the ends of the pieces down and they should snap together at the joint. The concept is that the pieces do not snap together in a straight fashion, but rather in almost vertical manner at the tabs.
If still not joining, perhaps you could get a friend or neighbor to come over and watch the video and see if they can get the hang of it. There's a "trick" to it that once you do it a few times, you'll be a pro at it.