Those things only seem to fail with neglect. Not changing your oil regularly will cost you in later miles. Zchild has well over 300,000 miles on his engine and it's still going strong. Nothing needs to be done inside the engine unless you **** up...generally. Change your oil, keep you cooling system up to date (prevent overheats), and don't thrash your engine all the time (especially while cold).
As far as complex DIYs (like head gaskets or piston rings), I think you don't see them for several reasons:
1. They don't need doing very often
2. they take enough time as it is, pics/video only slows you down
3. small target audience (people who have also ****ed up)