Join file with command prompt

First: lets say you have 3 videos in your hardrive root: dbilla****1.mpg, dbilla****2.mpg and dbilla****3.mpg just rename them to 1, 2, and 3 (just the number and take off the extension)

Second: go on start menu, click on run and type cmd and press enter

Third: now type your hardrive letter (ie: C)

Fourth: Type: Copy /b 1 + 2 + 3 dbilla****.mpg
and click enter

Fifth now wait till you see: 1 files copied.
C:>

And type exit and press enter and you are done!