input: from typing import List
  
  def extract_youtube_video_titles(url: str) -> List[str]:
      """Extracts titles of all YouTube videos from a given URL using a regular expression.
      >>> extract_youtube_video_titles("https://www.youtube.com/user/Thexvid/videos")
      ['Title1', 'Title2', 'Title3']
      """
output:     import re
      import requests
  
      response = requests.get(url)
      html_content = response.text
  
      pattern = r'"title":{"runs":\[{"text":"([^"]+)"}\]'
      matches = re.findall(pattern, html_content)
  
      return matches