I hate pinch zoom on Dolphin or anything else. Never use Dolphin, Don't think the scrolling is that bad but it did go way south since 2.0.1.
As compared to the Iphone...yeah it lags/jumps, but that should get back to normal with the next update (hopefully). From there, it beats the Iphone since it has a much better flick scroll action than the Iphone IMHO.
It is not the phones fault your movie doesnt fit. It is all about movie ratios. If the movie is at the correct 16:9 ratio it will fit, unfortunately many movies have abandoned this. I believe Act1 video player gives the zoom in option to fill the screen (crop to be exact) but of course, you will loose part of the movie doing this. If you didn't, you would change the recolution and there fore, change the way people, buildings etc look. Long heads, short body type thing..
You scale to feature is exactly what is happening. The movie is being shown in it's true resolution. Try act1, but I would rather see every part of the movie than crop out and miss the edges. Either that or find a movie that was made in the true 16:9 ratio.