Hello community.

I have never used PD. I feel like I have audio side of things under control with other software's but I have no experience with video synthesis, and I feel that PD may be a good place to learn something about it. As a total beginner and someone who is not familiar with the basic concepts involved yet I would like to gather some good GEM resources and some video/image specific PD tutorials that will walk me through some initial stages by the hand.
Can someone point me towards some things like that?
Is the PD extended package contain everything I need to get started with this?

The FLOSS manual is a good place to start.

http://en.flossmanuals.net/PureData/GEMIntroduction

Pd-extended has everything you need. You should also explore the GEM examples and help patches that come with pd-extended. You can open the help browser with apple-b on mac or control-b on windows and linux.