Hmm, I don't really have a lot of videos of us doing this. I think the only video we had was weaves. However, yes we do all the same techniques that everyone else does. I think it also depends on your size. I am a little over 6' so a big lab weaving between my legs isn't really an issue. We learn everything the same way.
However, yes there are different moves you can do with a big dog vs a small dog and a small dog vs big dog. I would have to look when I get home, youtube is blocked at work. But an example of something a smaller dog can do that a big dog can't is they can jump up and you can catch them, they can walk on your feet, etc. Big dogs, I have seen use a lot of props like one carrying an american flag around, lifting a flag. Standing on hind legs and giving you a kiss. However, there are Saint Bernards and Great Danes that do freestyle. One thing I would look at is "Rally Free" it's kind of like doing rally but with freestyle moves. Rally Freestyle Elements All dogs should be able to do all those signs. That's what they are made for. Now depending on your size and the dogs size they may not look the same but they should be able to do it. For example I know the guy that dances with a Great Dane does it to some funky music because he has to lift his legs up for weaves, so he looks like a Maori Warrior doing the War Dance.
Really though there are no set and hard rules on Freestyle. You want to play on your dogs strengths. When you see dogs doing amazing things in the dance it is because those are their strengths. Like Hemi for example, Spins and twirls, spinning left and right, is something he does really well and with a lot of exuberance. So we do a lot of spins in his routines. I can always count on him doing them exactly when I tell him and even a few times when I don't. The key when they do it on their own, keep going, act like nothing happened. I guarantee you all the videos you see, not one dog did everything perfect and those dogs made stuff up on their own or didn't do something they should have. They key is the handler doesn't let on and you don't know. Now, after working with Gloria at dog scout camp, Hemi's weaves are outstanding, we really had a hard time getting them down but after camp he just bloomed. We were actually practicing last night. He never missed a weave, figure 8 weaves, walking leg weaves. Changing sides like from left to right or right to left and continuing in a heel or coming out from weaving under my leg and right into a spin or come out from a weave and spin and right back into another weave. Another thing is Hemi now backs up in a circle with me in a perfect heel. We can do big circles or me just spinning on one spot. I was working with him weaving backwards through my legs last night but that's a long way off.
One to look up, look for Canine Musical Freestyle and Attila Szkukalek, he does all kinds of different and unique things with lot of large dogs.
Really though, and honestly, the way I look at it. It is just a fun thing for Hemi and I to do. He really enjoys it and smiles the whole time and well this just makes me enjoy it as much. Training session like all things should be kept short. We do a half hour a week and that's it, this is where we actually sit there to music and do nothing else. However, like out walking, I may just ask for weaves while walking. I may ask for him to switch sides. I may be fixing his breakfast and before we eat we have to do figure 8 weaves. Keep things short and sweet and reward and praise. Also start slow and build. For example working on leg weaves, start by treating every leg weave, then every other leg weave, then when they do 4 in a row, then 8 and so on.