Hi Michelle and welcome to our community
Part of this will depend on exactly what you intend to
record. For example, let's say you intend to show your audience how
to type text into Windows Notepad. Now you could just open up
Notepad and begin recording, but it is probably sized way too large
and you are wasting space. So you decide to size it much smaller.
After changing the size to be much smaller, you might record a way
cool really small project that will stream well. But what if you
need to also show your user how to save the file? If it's too
small, the File menu may extend beyond the recording area. Then
what happens when you click the Save option? See that substantially
larger dialog that results? Well, that size is what will probably
be your determining factor there.
Personally, my own "sweet spot" is 640 x 480. But your
mileage and needs will probably vary. Unfortunately, there is no
"one size fits all" for Captivate projects. In some cases you
simply cannot avoid recording at a large size. For example, if what
you are recording requires a full screen.
The general guideliine is that the smaller you might make the
recording area, the better off you will be.
Cheers... Rick