Googlebot-Image
Google crawls the site for images and indexes the images.
Googlebot-Video
It crawls the site to make videos appear in Google Video searches.
Roles in robots.txt
• These lines allow these bots to access the entire site.
• This means you are allowing Google to crawl and index images and videos.
User-agent: Googlebot-Image
Allow: /
User-agent: Googlebot-Video
Allow: /