so if I'm reading this right, you now have a video file and a corresponding mp3 which you want to combine, right?

This is really easy to do in sony vegas.

1) open Vegas,

2) drag the video onto one of the video tracks

3) right click on the "voice" track (the one that has audio from the video file on it)

4) select "delete track"

5) drag the mp3 onto one of the audio tracks

6) click on "make movie" at the top of the screen

7) follow the instructions!

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