If you can press on it and feel and squishiness, it's fat. However, the lines you were referring to is called the Apollo's Belt...a physical trait (which IS muscle - your obliques) that most guys would kill to have.
Here is your video. I looked you up on YouTube and copied the embed code. I'm not expert in the least, but you look like you have the makings of the coveted 'Apollo's Belt' and it is the muscular piping from your obliques down and around your lower abs.
I've got this problem and I don't like it, whatever people may covet. It has the effect of creating a little pocket just above the crease that looks like fat but feels like muscle. I'd trade it away in a heartbeat.