Again, a highly one sided video of part of a bigger event. Unless the full facts are released the only two comments I'm prepared to make to make are that I would have spoken to the passenger who wanted the name of those employee. I would have told him that these events are nothing to do with him, that is my job. If he disagreed with me, I would have left him behind. Secondly, the Gate Agent knew how to really inflame an already bad situation.
Unfortunately, too many people drag far too much stuff past the gate into an aircraft. They seem not to care that their luggage won't fit or that others may be inconvenienced by their selfishness. I'm rather lucky I have not had to deal with this too often but either the luggage is properly stowed or its owner will not be flying. Explaining this nicely is the challenging part of the job.