YouTube Video Editor
You can use YouTube Editor to Trim and Combine videos, Add Music and customize clips with special tools. But this can be done perfect only with the PC. But these are the days where people take their phones Shootout a video and Upload them to YouTube, I had come up several time with some messy starting in videos in such cases I wish to have a trimming tool for my Phone.
YouTube for Android now lets you trim your videos before uploading.
Editing a video is not so easy, you could find some option somewhere in your phone gallery or external Video Editing applications, But now Youtube allows its Android Users to deal with this editing work in its own application.