I am referring to those video compositions where you have separate clips at the same time, moving in and out and being resized.
they are very popular fror music videos and TV ads

have a look at this one (but I have seen others much more elaborated)

dior-homme-sport-judelaw.mp4 - YouTube (http://youtu.be/99oKxMs8Dfs)

thank you
Federico

Hi Federico,
Unless I'm missing something, (its happened b4 :), it is just using the pan crop window to adjust the size of different video layers.
See here for a starter-
Learn to Pan/Crop in Sony Vegas (http://www.sundancemediagroup.com/tutorials/pan-crop.htm)
cheers

so do I just use key-frames with Pan crop? I am trying to achieve that transition at secs 4-7

ok cool, you mean the eyes yeah? I'll take it as yes.
Take your shot of the face
Use pan crop to get the framing you want ( zoom, blacken edges etc).
Either render this out to your preferred intermediate, or save as a .veg.
Either way, drag it into a new comp.
Go into pan crop again, draw a rectangular mask from the centre to the left side of frame,
So now only the right eye/face is visible.
Animate the whole mask to appear ( or disappear ) to your liking.
Duplicate the track,
go into pan crop on the new copy,
first change mask properties on your 2 keyframes to negative, so now on your new track the left half of face is showing.
Now change your two key frames again to reflect your preferred animation (opposite to right side in your sample).
Thats pretty much it I think.
:)

thanks Gerald
I referred to the eyes that than fade to the bridge that finally expands full screen

will try your suggestion, thanks a lot for your help!

still trying but cannot completely grasp what you suggested

when you say "Go into pan crop again, draw a rectangular mask from the centre to the left side of frame," I tried doing that but the anchor tool doesn't seem to allow me to draw precise rectangles ...or am I missing something?

a similar effect is seen on TV series (like the Brady Bunch
The Brady Bunch Theme Song From All Seasons - YouTube)

another great example is here: Intersections - Diptych (Split Screen) London - YouTube
<Intersections - Diptych (Split Screen) London - YouTube
dex=84&feature=plpp_video>
&list=FLfVPsb1_O97PsYtF8OhU__A&index=84&feature=plpp_video (although the shapes do not expand or reduce)

Use the Track Motion tool
You wont believe how easy it is
:)

thanks Gerald. I spent a good amount of time trying and I got very close to understanding how to make that last clip above( "Intersections")
I guess I wasn't familiar with the concept of nesting projects to a new track, and then using track motion.
Still,I don't quite understand yet how to replicate the final few seconds, where all the screens then rotate showing the credits, that's really well done.
still not 100% familiar with the differences in why you would use track motion vs pan and crop but slowly getting there....

the anchor tool doesn't seem to allow me to draw precise rectangles ...or am I missing something?

You can draw precise rectangles by editing the anchor points manually -- enter the X and Y values directly in the sections to the side of the crop window.

But for most rectangles, you can just crop without using a bezier mask.

I guess what I meant is that I thought there would be a quicker way to draw "precise" masks (square, rectangle....) asking Vegas to keep the angles the same. (like to use specific predetermined shapes, like when you use the cookie cutter)
there doesn't seem to be such an option

Well, that's what the cookie cutter is for. :)

But like I said, squares/rectangles are easy simply using the crop tool; no need for the bezier mask.