It shows that Media Player Codec is missing. Is it safe for me to install this?
There really is insufficient information to give a definitive answer if it is legit/safe or not.
This is one of the most common tricks to get you infected, of course it would say it is safe to download, even if it were infected. For me the bigger deal they make about it being safe to download, the more suspicious I would be.
A screenshot of the notification may be helpful.
What were you doing when you got the notification about a new codec pack ?
Do you actually have some sort of codec pack installed ?
I have the k-lite codec pack installed, but I don't believe that checks for updates or if it does I don't let it do it autonomously.