here is a video, maybe you can help identify?

Umm I know when I start my car sometimes it starts knocking (like people do on a door) then you put it in gear and it stops. Im assuming I need new engine blocks.
How many are there?
Where are they located?
Do I just jack up the engine, unbolt and re bolt new ones on?
Do I have to remove anything before I jack up the engine?
Also sometimes I hear whirring from my gearbox...
Just want her running right so I dont break it

Any help would be greatly appreciated!
Cheers
Jay