Help! Video Mix down

[D10S]

I need to mix down all my video tracks into one so that I can add a letterbox to it all, how do I do that?

 

[Batutta]

Highlight every clip in the timeline (apple A or Select All in the menu), select nest items, this will create one long clip with your sequence nested inside. Then add a letterbox to it...However, I prefer to add a slug on the top layer and add the mask shape filter to it. Click invert and select horizontal to 100 and vertical to around 75 for a standard letterbox. The advantage is that you can slide the clips below it up and down if you need more, less headroom.

 

[D10S]

Thanks,
I just did a nest and created a new sequence and dropped a letterbox effect on that.