The same question was asked just a day or so ago. And the answer is to use the standard Windows method in either storyboard or timeline view. Left click on the first frame/video you want to move, then hold down the Shift key and left click on the last frame/video. Everything in between will now be highlighted and can be moved in its entirety.
Or if you have VS9 or 10, use ripple editing. In VS10, the control is found to the top left of the timeline. Mouse over and it will tell what it is. Click it to toggle it off or on. When it is toggled 'on', make sure you click in the other tracks (title, audio etc) to make sure these are included in the ripple editing. Then just drag your new video to the place you want it, drop it in and everything to the right of that point will move right to accommodate it.
BUT - - if you just want to insert something into an existing video you do not have to move everything else manually to get it in - just drag and drop the new item into the timeline where you want it to be and everything else will move along - even if you do not have ripple editing enabled. The thing that ripple editing does is to move everything in the other tracks as well so that all tracks remain in sync.
Just to clarify a bit to what Ken and Brian have stated. On the mainvideotrack you can just drop a clip in and the rest of the clips will move on the timeline. However, on all other tracks (overlays, audio) this does not happen. You have to manually make room if you want to insert a clip between two others.