I don't see anything that would stop him from stopping to fight them wherever he wanted (as long as it had enough space and wasn't a breakable platform itself), they just wanted to show off the more interactive, seamless environments and character agility I think....
And yeah, early stuff folks, the environment looks worse than TriG and the Tigrex look like PSP yet the Rathalos like Tri. Tri G is the new game you can expect in the coming months/year depending on region, 4 is way off it seems, as should be expected.