I am writing this post to help others who are preparring for Facebook Interview. Here is my experience and questions that were asked. All interview rounds at Facebook are 45min long.
Note: I am still waiting on the result of my interview.

Phone Screen :
(5min Intro + 35min Questions + 5min Questions for Interviewer)
Stack related question for validating parenthesis (Leetcode Medium)
Palindrome permutation (Leetcode Easy)

Virtual Onsite:
Facebook uses BlueJeans application for virtual interviews. Following is the order in which I had 5 rounds.

Behavioral:
(45min discussion)
You really need to know each of every word on your resume. This felt like a technical round more than behavioral round. I wasn't asked typical behavioral questions but rather deep dive into technology I worked on. Interviewer literally grilled me on it and by the time we reached to situation related question like conflict handling, time was up. This was an very unexpected experience for me.

System Design:
(5min Introduction + 35min Designing + 5min Questions for Interviewer)
Unlike the other Facebook interview posts on Leetcode, my experience was little different. The question I was asked was combination multiple system design questions.
Question: Design a streaming service like Netflix with lots of features (each feature can actully be mapped to different system design question)

Coding Round #1:
(5min Intro + 35min Questions + 5min Questions for Interviewer)
Binary Search related question (Leetcode Easy)
Sliding Window problem on an Array (I didn't find exact question on Leetcode but I would rate it as Leetcode Medium)

Coding Round #2:
(5min Intro + 35min Questions + 5min Questions for Interviewer)
Level order tree traversal question (Leetcode Medium)
String manipulation (Leetcode Hard)

Coding Round #3:
(5min Intro + 35min Questions + 5min Questions for Interviewer)
Binary search related question (Leetcode Medium)
Backtracking related question on expression operators (Leetcode Hard)