Yes, pretty much - it looks like you created a circular feathered mask?
I kind of cheated with my own quick and dirty example above -- I didn't do it in Vegas but saved the two frames and then did it in Photopaint (my Photoshop :)

I'd have video events going on in in most parts though some still may be used. It can get complicated -- matching or complementing compositional elements between events as they occur and transition..One way I've been toying around with is the use of Add and Screen track modes over Source Alpha ones.

I suppose I'm being a bit unrealistic to find some template or tutorial because it really just comes down to elbow grease and lots of masks, feathers and keyframes...

I don't think you'll find a Vegas tutorial because most people don't seem to want to do something like this in Vegas (they'd rather use AE, etc), but it is nothing more then a mask.

I've done it several ways: using a biezer curve mask with a feather, using an animated gradient, an animated other generated media, a mask rendered from a video, etc.

"I've done it several ways: using a Bezier curve mask with a feather, using an animated gradient, an animated other generated media, a mask rendered from a video, etc." Thanks, The HappyFriar, you provided some alternatives in the latter part of your list to look into besides Pan/Crop masks.

There are many ways to "skin the cat" doing this kind of work and again I have to say that one of the best resources for inspiration and thought provoking tips is watching After Effects tutorials. I've bought a lot of what I've learned from them to compositing with Vegas. The only cost to watching them is bandwidth and time.
So many times just working in Vegas something that has stuck in my brain from watching an AE tutorial has sprung out of the back of my head to give me an easier way to get the job done in Vegas. Other times working in Vegas I've thought the standard of the outcome just wasn't good enough and inspired by some dim memory of an AE tut I've worked it a bit more to get a better outcome.

This kind of work is mostly just hard slog, sure it is easier in other apps but they are not mandatory and the techniques and concepts are the same even if the tools look different.

Bob.

Sorry if this is a dumb question but can't you get the same result (a whole lot easier) by simply using a Linear (Soft) Wipe and increase the feathering amount? I just gave it a quick try and it gave me a very nice result. What's the advantage of creating a mask?

"What's the advantage of creating a mask?"

A mask gives you more control, you can keframe the shape, feathering and transparency. You may or may not need all of that and indeed other simpler techniques might be the best fit. One thing that Vegas lacks that other apps provide is a simple way to expand or shrink the mask, would be nice to have that facility. On the other hand one can create a matte and the size of that is very easy to change in Vegas.

Bob.

Thanks, Bob, for your responses.

Yes, indeed, a simple feathered wipe wouldn't do the same job as carving out the left side of a silhouette in event A to somehow gracefully meet or fuse with some incoming right hand element in event B, etc. That said, I also have to keep in mind what you've sometimes told me... I can get too carried away in uber-details and could spend years making masks and croak before the video is ever finished - lol. The blessing/curse of my artsy-fartsy visual style.

AE tutorials, good idea -- did that once with the same "lemme see if I can adapt/steal the essence of this into Vegas..."

One thing I wish that Vegas had and I think AE and others have -- I don't know since I have no other and only toyed around wit a really old AE (3.1) -- is the ability to draw out the route of a pan and/or zoom with a Bezier which gives far more maneuverability than just the attributes of the keyframes. In other words, if I wanted the pan/zoom to follow a mild "S" curve from bottom left to upper right, it could be drawn out. Or maybe I'm just dreaming this is possible :)