How do you unlock an alternative ending in Battleblock Theatre?

I've seen a few YouTube videos with the title 'all endings' for Battleblock. I decided not to watch these until I manage to get it unlocked on my own playthrough.

My thinking is that it's probably one of these:

• Get an A++ on all stages
• Do all time-trials
• Complete the game on insane mode
• Free all prisoners
• All of the above?? =,[

If you don't know of any alternative endings but have done these then that's probably just as informative.

Otherwise, if there really is another/more ending(s), how do you unlock it/them?

Solution 1:

There are no alternative endings in Battleblock Theater. If this was the video you were referring to, it seems like they were using "all endings" to refer to the chapter ending cutscenes, since there is no difference between that video and any other compilation of cutscenes in the game.