Actually, I do sometihng most people here would consider insane. I video-chat with my girlfriend (we don't live in the same city), but I only use the video part, I disable the sound.
I do this so that we can chat in writing (windows live messenger), and so that we have some "company" when studying, without disturbing each other with the noise we make while studying

Not insane, at all. Actually, that is very sweet!

Here's some insanity for you:
I met my boyfriend (he's in France, I'm in California) on a computing forum with no intent to meet (in person).
When we first started video chatting, after writing for a few months, we had so many verbal misunderstandings that we got very shy and often used text chat with no sound, as well.

It helped a lot. This way, we learned to match facial expressions with written ones, and it made the conversations go lot smoother...

Now, when I yell at him, he understands perfectly  

... Also, some people can be uncomfortable when talking using a videocam, in the sense that they can be in pajamas at home, in underwear, or doing those little things everyone does at home, and it's embarrassing for them to let others see them like that.

Forgive me if I am too much OFF the thread's subject, but Lashiec's comment made me think of a Danish commercial (in English). The company JPS started out many years ago, making men's underwear only. Later they also added a minor line for women, but in general their ads addresses men only in a unisex'ed way (knowing that any female partners also will have a say).
This .WMV may be rated as NSFW (not suitable [attachimg=#] for work) in the USA:

http://curt.dk/underwear.wmv