Vaazha 2 major mistake

So the story is set in 2017-19 when the students are in +2, as they mention _Lucifer_ release which was in 2019 and also Mujeeb sir catches everyone's Android phone in class. Then today I noticed that for trapping Alan for his sunath program they come up with DVD and CD. Can't they just watch it on their phone? DVD feels outdated for 2019. I guess nobody watched porn on DVD during that time.