It depends upon what kind of editing you're wanting to do. If you only want to upload to youtube, go to the gallery, select your video, click share, and choose youtube. If the video is larger than 1 GB then I would copy the video to the pc and edit it with any software that can edit a 3gp file. Perhaps someone can chime in here for a better option?
I can't see doing any editing other than a few simple cuts on the device itself. I'd suggest transferring to a PC and editing there if you intend to do anything more.
But, then again, I'm used to using fully-fledged video editing apps on PC's anyway.