Flickering Horizontal Lines

For quite some time now (Well over a couple of years) I've noticed small flickering black horizontal lines on my monitor usually coming out of the bottom-right hand side of the screen (Sometimes top-right). But they're not just lines. It's more like a graphical artifact. The line actually looks like dots, and it flickers until it starts getting shorter and vanishes (The movement of the line kind of reminds me of Snake). It doesn't always happen but often does happen on YouTube, seemingly exacerbated by scrolling.

I tried taking a screenshot of it, but it doesn't show up on screenshots.

The monitor is a Hanns-G LCD (28"). I wouldn't be overly surprised if the monitor is faulty as I've not been able to wake the monitor up from sleeping for years (I have to physically turn it off and then on).

 

If the problem doesn't show up in a screen shot it is a problem with either the monitor or the video cable usually. Also having to manually wake the monitor up from sleep points to a monitor problem.