Hi Fred, and welcome to the forum.
First off, you're probably not missing anything regarding your outputs. What you are probably not aware of, though, relates to your original video. First off, while mpeg-4 is a popular format associated with small files, and is fairly easily edited, your version of it is not standard in video editing terms. 1024 x 768 is by no means a standard frame size. The usual sizes would be the ones you have tried outputting to (720 x 480, 1280 x 720) plus ones like full HD 1920 x 1080 and 4K 3840 x 2160. But we won't worry about those last two for now as there would be no sense in choosing either of them for outputting your video.
The really surprising thing about your original video, though, is the frame rate of only 5 frames per second. I am not even sure why or how that frame rate could produce smooth-looking video -- though admittedly, for a conference call there would not be much movement, let alone fast movement, and no panning of the camera which would appear strange with such a low frame rate. The normal frame rate would again be what you used in your output files i.e. 30 frames per second (actually and more accurately 29.97 fps for NTSC countries, which I assume you are in.) Again we probably don't need to go into whether that is 30 interlaced frames or 30 full frames (30i or 30p). And you could also have 60 fps.
The bitrate (sometimes called data rate) of your video is also pretty low at 24 kbps though some mpeg-4 codecs can still produce good quality video with such a low bitrate. Bitrate is one of the most important factors influencing quality in a video. Usually, the higher the bitrate, the better the quality. But increasing the bitrate also means that you are increasing the size of your resulting videos. That explains -- at least to me!
-- the significantly larger clips produced in your last three output examples since apart from anything else they are using bitrates 4 times (10 Mbs) and 8 times (20 Mbps) higher than your original video.
In addition to that, to get from a frame rate of 5 fps to 30 fps Video Studio is in effect having to invent new frames -- 25 new frames per second -- to get it up to the output frame rate. It does so by repeating existing frames. Again, I'd have to say I don't think the resulting video would look particularly good, but again would be 'saved' by the small amount of movement in a conference call. I suspect your first output example is the size it is (46 MB) largely because of this factor and also the mpeg-4 codec used by Video Studio, since the bitrate is largely the same as your original (2.5 Mbps). And by the way, in video terms 46 MB is itself pretty small for a 6.5 minute video!
One other small mystery remains. You say you "capture" the video in VS. What exactly do you mean by that? Can you give a step by step account of how you go about capturing the video? Normally, I imagine WebX would create a video of the conference call and store it on (probably) an SD card in the phone set-up or a computer. Again normally, we would simply plug the SD card into the computer with VS on it and use VS's "Insert Video File" command (when you right click either the library window or the timeline), browse to the SD card and open the relevant file which should then appear in the library or timeline. You could also copy the file from the SD card to your computer's hard disk, then browse and insert as described above. Did you do that or something else?
Do you get any message pop-up when you insert your video clip into the timeline to start the new project? The message would ask if you wanted the project properties to match those of your clip. If not, then go to Settings > Preferences, and on the General tab, about half way down, make sure the box beside "Show message when first video is inserted into the timeline" is ticked.
If you get such a message, then after you finish editing, and want to output a new and edited video with the same properties as the original, you go to Share and at the very top, tick the box which initially says Same As Project Properties, though in this case, you could also select Same As First Clip (which you get by clicking the little downward pointing arrow to the right of the box). See where the green arrow is pointing in the image I have attached below.
I bought VS Ultimate two days ago for work. Every video I'll ever make starts off as a recorded meeting made from WebEx (similar to Skype, GoToMeeting, GlobalMeet, etc.). It's always going to be somebody sharing their screen, moving the mouse around, and talking about various things. I'd like to be able to edit the videos for content (trimming, mostly). Which one of the output formats is best for what I need? I'm working with my first file now and am getting frustrated. Here's what I've tried: