I can't shot videos because I use software that prevents me from seeing them so this whole thread is a wall of nothing for me. I will just share the ones I like and you can find them if you want.
NES:
XEYYZ- First game I ever beat awesome ending and amazing feeling since it was a hard as hell NES game.
Super Mario Bros. 2- Love that ending to this day, also first Mario game I ever beat.
Friday the 13th- not the ending NEVER got that far but the Game Over screen is the ****, You and your friends are Dead. The End.
SNES-
Super Mario World- still my all time favorite Mario game and the end credits were always cool treat. What always bothered me is I NEVER new about that hidden level so the image with those under water bomb guys always bugged me because I could never find them so I thought it was just a glitch they were in the end credits until one day I googled Super Mario World 100% and discovered I had been missing a level all these years.
Kirby Super Star- I like the Spring Breeze, Wilky Way Wishes and Great Cave Offensive they were pretty good.
Sim City- this is a hard one to get to but it is well worth it if you do, the Game Over Screen is also kind of fun to trigger if you really try.
Genesis-
Sonic 2- first game on Genesis I played/beat still loved the ending had a nice little mini movie was pretty cool at the time and loved the music.
Turrican- I like everything about this game from the music to the levels the credits are built into the menu so you don't even have to beat the game to see them, something they must have known most people would not accomplish without cheating anyways so they knew what they were doing.
Toe Jam and Earl 2 Panic on Funkotron- one of my favorite games had multimple endings well two I think both pretty good.
Game Cube-
Melee, nothing new to add it was awesome.
Mortal Kombat Deadly Alliance as with most MK games the credits were pretty good this was the best though
That is about it for me, I honestly don't beat or finish that many games, have beaten more than this but none of they are anything special.