@John S.- I have done some video work for past trip reports and gear vids, but haven't in a while. I was shooting with a Nikon D7000 and a 35 f1.8 lens at the time, not a GoPro. I downsized to a smaller form factor camera that helps make great photographs, but lacks the video capabilities.
You can create well crafted videos using iMovie and nothing else, other than time and creativity. If you're looking to bang out a piece to submit for Sender Films or something of that ilk, you're going to need to pony up for some serious post processing video software and all that goes into supporting large video files. For simple video editing to share with friends and family, quality results can be achieved.
Get yourself a GoPro, purchase a Vimeo account for uploading and sharing finished work, and have fun with it and see what you can create. I'm not sure what Jake D. is pissing on about.