well source has its own recording...you can just use windows movie maker to edit it.
you can also convert it with the source recorder if you have the right codec, just download the uhh what was it...xvid codec i think then in console type startmovie name avi and pick the xvid codec then play your footage with playdemo name. it will go at like 2 fps and may take awhile depending on your computer but it is the easiest and best way to convert it. you may want to lower your resolution to the appropriate setting before converting it, or you could change that later either way.