Joining videos and making screencaps

[hellonewyork]

Hello, I have two questions.

I was wondering if I can join videos on a Mac?
I know Quicktime can, but the resulting video isn't really smooth.
I tried doing this on iMovie, but I don't like the black outline (is there a way to get rid of it then?) and it doesn't preserve its original quality (not even that close x_X)

My second question is, is there a program that allows me to create screencaps like this:

Preferably free programs please.

 

[John Doe 57]

Merge AVI Files:
http://www.objectifmac.com/dvision.php

Combine Multiple Movies:
http://www.qtsync.com/

Not sure about how to make a screencap like that.