Extremely unresponsive client. Who turned rude and abusive on seeking clarification.

[#1]

Please suggest a way to highlight such clients to Upwork.

He did not want to give any clarification. I created a quick prototype to explain my understanding of the project. Here is what he wrote. 

"i am busy as #^$^ .... i have no &^%%^ing time for a call.... i asked u to convert written test to video test......... (and a lot more that I don't want to post"

He had sent a list of Youtube videos that I did not want to integrate into training without any clarity on the IP status. He did not have any understanding of an LMS or how a QA can't be just inserted in a video.

[#2]

The way to deal with a client like this is to report the abusive message by clicking on the three dots to the right of it, although chances that Upwork will take any action are very slim. Then tell the client, "I'm sorry, but I don't feel that I'm a good fit for your project. I'm going to close the contract so that you can look for another freelancer." Then close it.

But as for, "He did not have any understanding of an LMS or how a QA can't be just inserted in a video" - I have no what you're talking about, either. And did you tell him how to get clarity on the IP status, explain the repercussions, and/or offer to find more appropriate footage yourself? It's up to you to explain things to your clients and manage the project - you're the expert, not them.