I'd like to recommend HD video editor mac to you, I always use it to edit video and make funny video for uploading to Youtube, it's easy to use and the quality is awesome, you can crop, cut, join, edit video with it easily. It also embeds many special effects, you can even add text to video or add background music, that's pretty cool. It worth a try. Here is the free download link.
And here is a step by step guide about how to use it
Hope it helps. Contact me if you have any other question.