Notes:

For anyone that doesn't really know what is going on, Computer (Insane) is has an extremely defensive AI… and exploiting it is as fun as ever.
The creator of the video is "FunnyWarcraft3", and even though his channel name seems a little too "clickbait" he is actually a really good player, like… really really good player, he is well known for his series of "1 race vs 11 insane computers on the same team" or even his comebacks and plays on Online Battle, if you want to see some funny exploits or good plays, check him out.
If you want the precise time where this happens in the video, it happens in 48:46
(I had a debate on myself if this was going into Video Game Logic or Gaming, but since its about bad AI, I decided on this gallery then)
(Also, if anyone complains about the size and says "WHAT IS THIS, PICTURE FOR ANTS!" I just gonna say… KYM STOP MAKING MY FILE NOT BEING APPROVED REEEEEEEEEEEEEEEEEEEEEEE)