That title works well. Here are a few polished alternatives depending on the style you want:
- Langur Monkeys Grieve Over a Fake Monkey (simple and clear)
- Langur Monkeys Mourn a Fake Monkey in an Emotional Scene
- The Surprising Reaction of Langur Monkeys to a Fake Monkey
- Langur Monkeys Show Grief Over a Fake Monkey
- Emotional Moment: Langur Monkeys Grieve Over a Fake Monkey
For YouTube, “Langur Monkeys Grieve Over a Fake Monkey” is concise and attention-grabbing.
