How to loop a specific file in HTML?

I would like to know if it's possible to loop only a specific files like video/mp4? In the folder I have also multiple files and sub-foldes and the html load every elements.

{% for file in video_files %}
<video controls width="250" height="250">
<source src={{ url_for('static', filename=file) }} type="video/mp4">
</video>
{% endfor %}

This is the code.

Python with Flask

from flask import Flask, render_template
import sys

app = Flask(__name__, static_folder='static')

import os

path = 'static'

@app.route('/')
def index():
    files = []
    # r=root, d=directories, f = files
    for r,d,f in os.walk(path):
        for file in f:
            files.append(file)
    video_files = files
    return render_template('index.html', video_files=video_files)

if __name__ == '__main__':
    app.run(host='localhost', debug=True, threaded=True)