Camtasia gives you more flexibility with the editing process. especially when trying to sync audio, video and still media.
On first using it it looks complex but is actually very user friendly.
My advice would be if your creating and producing your own video for the likes of Youtube, produce it in .avi format. i've tried the "recommended" formats and all fall short on either sound or visual quality.
Below is a neat little piece of S/W to add that little extra to your video creations. I use it to help friends/family add something different to their videos and it's compatible with both camtasia and Windows native video production S/W: