oh ok, if your doing it that way, it can still come out fine. actaully, they look cool, a fisheye effect.
anyway, this is what you gotta do to fix those seams. start at one side, and go to the next frame, and adjust the contrast, brightness, and all that crap till you get it to match perfectly. do um all. then go fix up the trees and shit with the clone stamp and healing brush tools. touch up any major flaws with a brush. then, go and crop out all the jagged edges, and walla! your done. if you dont feel like dick around, im VERY bored, ill do it for yah. shit, just email me the files and ill play with it to entertain myself for a while. infos in my file.
ill post one i did of a big fallen tree on a DH mountainbike course