Watch that. It's not even vocally amazing or aesthetically appealing, yet it doesn't fail to capture my heart. It's the effort they make to sing that song. It's the feelings they put into the song. It's the way they try to sing despite their lack of proficiency in a language not primarily their own.
If it were you, would you dare? Would you dare stand on that stage in front of several others, knowing very well you dont sing well, but you still would give it a shot? Would you continue singing despite the wrong verse you sang for your first line? Would you make the effort to put on all the make up, even if it's hideous or otherwise?
For all of their effort, I dont see why they should be jeered at or insulted at their lack of vocal talents. Whoever says that all good singers must have a good voice?