It's a forum game but...

[Lario]

... we come up with the ultimate "video but x happens" title. It's like the sentence finishers thread but it is a title that never ends.

I'll start:
Moskau but every "Moskau" is replaced with...

 

[Magikrazy]

...footage of a legend of zelda playthrough but every time link enters a dungeon it cuts to...

 

[DragonFreak]

Every let's play of a zelda game, but every time link opens a chest...

 

[Polymorph]

...It cuts to a Metroid LP but every time Samus shoots her gun...

 

[Weasel]

The Nutshack theme plays but every nutshack is replaced with...

 

[Polymorph]

...The whole Hunger Games trilogy but every word is replaced with...

 

[Magikrazy]

...the DK Rap but the phrase "coconut gun" is replaced with...

 

[Polymorph]

..."Watch for Rolling Rocks - 0.5 A Presses (Commentated)" but every Mario sound is replaced with...

 

[LN1]

...HP but every time Mario gets hurt...

 

[TPG]

...Every LazyTown episode plays but every time Robbie Rotten appears...

 

[Lord Bowser]

the opening scene from hotel mario plays but every time mario blinks...

 

[Magikrazy]

...every smiley on super mario boards appears on screen for exactly one frame but is replaced with...