Hopefully you have a good spec PC, what you'll need to do is one of 2 things;
- Download a basic video convertor that will take your raw video files and reompress them into something more web friendly, like mp4 files. Most software will let you choose the new video's size, so reduce the size from full HD to 720 or lower to help reduce filesize. If the cam films in 30fps, bring that down to 25. Search download.com or cnet.com for free convertors.
-Import all your footage into a video editing software like Premiere and crop out all the unwanted footage to physically reduce the overall length, then go ahead and use the software to output the video using the techniques in the 1st point above.