This video is intended only to educate people about how hackers crack passwords, and how important the strength of the password is, when coming to security.
If you are using a common password like test123456 which I used in the video, then the hacker will easily be able to know the plain text form of your password from the hash string. There is something known as Rainbow tables. These rainbow tables contain the password hashes of numerous commonly used passwords.
So the hacker will be to do a simple search with the password hash that he has, and if the password hash exists in the rainbow table, then that means the password is successfully cracked, and we have the password in a plain text. Remember that rainbow tables contain the password hashes of only the passwords which are commonly used.