How to delete watch history in Facebook activity history

If you go to your Activity Log in Facebook and click Photos tab in the left menu, you will find the history of watched videos in your timeline.

I assume, even if you watched auto-played video in your timeline, Facebook assumed that you watched that video and log that you watched the video. It indicates the history is not visible to others, only I can see it; however, I was uncomfortable that Facebook recorded my history in their database.

They do provide the way to delete the video watched history; however, you have to delete the video history one by one, which is gonna taking very long time to delete all histories. Not sure why Facebook does not provide the way to prevent logging at first stage or delete all at once. (or even if I delete from the history, does it actually delete from their database?)

So I had to find out the way to delete at once, or at least semi-automated.

Here is how to do semi-automated way to delete video watching history in Facebook Activity Log.

1. Open Google Chrome and log in to your Facebook
2. Click your profile
3. Click View Activity Log button in top right.
4. Click Photos on the left panel, then you will see the watched video list like below:
5. Click right mouse in any place in the page and open Inspect Element
6. Click Console in Inspect Element
7. Copy and Paste below code and press enter. You will see the histories are deleted

   var el = document.getElementsByClassName('_42ft'); 
   for (var i=0;i<el.length; i++) { 
    el[i].click(); 
   } 
   
   var el = document.getElementsByClassName('_54nc'); 
   for (var i=0;i<el.length; i++) { 
    el[i].click(); 
    setTimeout(function() { 
    console.log(i); 
    }, 100); 
   }

8. If you click Photos tab again, you may see other histories that still are not deleted, try to load more activities by scrolling screen to bottom multiple times and do step 7 again.

If your page is reloaded or logged out, then try again.

You may see the activities even if executed the script. Sometimes, it may take a time to see actual deletion. Try to execute again or check some period later.