Well, the video clip is whatever size it is. If you have a standard PAl project in Premiere and import a small video clip of size 340x200 then it will sit in the middle of the screen looking like a scene from 24. You can use the motion and scale settings to make it larger and fit the screen but it will be a digital zoom and will make the qualityy degrade quite a bit - not that it'll be great quality anyone if thawt's where you got it from - no direspect to whoever made it but it'll be a compressed file that will be noticable.
open a new project and click on the custom tab at the top choose desktop for the video type and then create the settings to match your video.
then it will sit in the middle of the screen looking like a scene from 24
Excellent comment Alan, made me smile.
Canon, Edius, Final Cut Studio, Always Progressive, Promotional Video Production