The point of this section therefore is to make you aware of this webpage
which shows how to install Flash, multimedia codecs and other useful packages
like Handbrake, SMPlayer and VLC.

(https://wiki.centos.org/TipsAndTricks/MultimediaOnCentOS7)

Whilst I am here it is also worth sending you in the direction of these two
articles from the Dedoimedo site which show how to create the perfect CentOS
experience.

http://www.dedoimedo.com/computers/centos-7-perfect-desktop.html
http://www.dedoimedo.com/computers/centos-7-perfect-desktop-more.html