Sticky? Y/Y?

Why are places like Facebook and Myspace so 'sticky'?

I decided visual aids would help answer this question, so have another screencast.

http://screencast.com/t/w32PmVKJhI

Facebook how to

Click the link below to view a screencast of how to add photos to your Facebook profile.

http://screencast.com/t/ZwJCfcrxI