Okay, I probably have the name wrong of the vehicle (I only really know the ship's names). On the fourth mission, I get all the way to where you have to put the rope (on the speeder) around that huge walking vehicle's legs. How do I do that? I get the little movie scene of the rope being thrown around his legs and the rope never seems to hook on.
I also go through the legs and it never falls. How do I destroy that huge walking vehicle?
If it goes to the "movie scene", the tow cable is hooked. You're not suppose to go through the legs, but rather around them. Make sure you don't go too far from the walker's legs or the cable will break off. You have to go around the legs three times and then you'll see a cut scene that says "Cable out let her go".
I find your lack of faith disturbing
When you click the secondary fire the tow cable should be launched. You know the cable is hooked when it changes your view. Try coming up from behind the Walker, on the right side. When its directly on your left hit the tow cable. It'll take several attempts to get used to it, but basically you just go around in circles. Personally I have found it better not to slow my Speeder, just let it go at a normal speed. You'll get the hang of making the circles, eventually just holding the joystick in one position.
1. You go up and down too much. The Speeder automatically hovers so don't worry about touching the ground -- although don't slam it hard!
2. You get too close to the legs at explode by hitting them.
3. You get too far away and the cable is lost. If this happens, you need to make tighter circles. You're actually farther away than it appears at times.
Hope it helps. It was the Walker on Level 4 that first brought me to this site a few years ago. Didn't post then, but read the tips and walk-throughs.