How to update multiple videos/LiveBroadcasts one by one (using list of their ID's), using YouTube API in Python?

I know that it's impossible to bulk update videos, using YouTube API.

How can I update several videos/LiveBroadcasts in Python by their ID?

I have working script sample, but it applies only on 1st video from list:

###Getting Credentials
***
###GET ID's list OF ALL BROADCASTS  
def main():
    youtube = build('youtube', 'v3', credentials=credentials)
    request = youtube.liveBroadcasts().list(
        part="contentDetails",
        broadcastStatus="all",
        broadcastType="all",
        maxResults=100
        )
    response = request.execute()
    for item in response["items"]:
        response_id=item["id"]
        print(response_id)
###Make all ID of Broadcasts UNLISTED
    request = youtube.liveBroadcasts().update(
            part="status",
            body={
              "id": "{}".format(response_id), #applies only on 1st video ID, first line from "response_id"
              "status": {
                "privacyStatus": "unlisted"
              }
            }
        )
    response = request.execute()
    print(response)    
if __name__ == "__main__":
    main()

print(response_id) is:

1st video ID
2nd video ID
3rd video ID
etc
...

You have an incorrect indentation. You are looking for executing youtube.liveBroadcasts().update function at each iteration in the loop for item in response["items"]: so you should have:

    for item in response["items"]:
        response_id=item["id"]
        print(response_id)
        ###Make all ID of Broadcasts UNLISTED
        request = youtube.liveBroadcasts().update(
            part="status",
            body={
              "id": "{}".format(response_id), #applies only on 1st video ID, first line from "response_id"
              "status": {
                "privacyStatus": "unlisted"
              }
            }
        )
        response = request.execute()
        print(response) 

Instead of:

    for item in response["items"]:
        response_id=item["id"]
        print(response_id)
###Make all ID of Broadcasts UNLISTED
    request = youtube.liveBroadcasts().update(
            part="status",
            body={
              "id": "{}".format(response_id), #applies only on 1st video ID, first line from "response_id"
              "status": {
                "privacyStatus": "unlisted"
              }
            }
        )
    response = request.execute()
    print(response)    

This is the reason why you have as output the following, as in Python when using a variable assigned in a loop, the last assignment is kept when quitting the loop scope (that's why only the latest video of your list got updated successfully):

1st video ID
2nd video ID
3rd video ID
etc
response