How to allow user to access my content only if they disable adblock ?

Hey guys, I have a website and I want to make it accessible to visitors only if they disable their adblock just like firstrow.eu. Since I run pop up/pop under ads on my website, I would like to know the process of how to do it. I manage to pull in massive traffic from youtube and my website is doing well.

I have three modes of income.
1.YouTube adsense.
2. Pop up/Pop under ads.
3. Video Hosting sites that runs ads.

Sometimes this can help you https://blockadblock.com

thank you very much labba that was a quick reply.