Should I update libav codecs lirary from 9.18 to 11.3?

Concerning Ubuntu 14.04 LTS (Trusty)

Software Updater lists but does not allow ticking (checking) of box to update:

[_] Libav codecs library (additional codecs meta-package)

It reports:

Changes for libavcodec-extra versions:

Installed version: 6:9.18-0ubuntu0.14.04.1

Available version: 6:11.3-1~trusty

This update does not come from a source that supports changelogs.

My streamed video playback is terrible (possibly because of bloatware on an old machine) but I'm wondering if I should update codecs.

1. Is there anything else to consider
2. How do I get it to automatically update (if it isn't properly)
3. Should I stop worrying and stop interfering?
4. I'm uncertain how Libavcodec54 relates to the version numbers above.
5. I don't want advice that leaves my system vulnerable or requiring future remembering of what I've done previously. e.g. see AskUbuntu question 851190

Advice pitched for a noob, please.