Handbrake - Open Source Video Transcoder

HandBrake is a multi platform tool for converting video from nearly any format to a selection of modern, widely supported codecs.

Download Link: https://handbrake.fr/downloads.php

Secure Adobe Flash Player Updates

From the Apple icon, select System Preferences

Click Flash Player, you will see what version you have installed.

Check for updates. This will connect directly with Adobe Flash Player site. 

If updates are available just follow instructions to install. (You will be prompted to install further updates automatically...it may be wise to click on "notify me to install updates" just to be on the safe side and follow the above procedure every time you are notified.

If you want to check installed plug ins - Safari > Help >Installed Plug Ins