Was AWS Secrets Manager removed from AWS CLI commands? If I enter: 

 aws secretsmanager get-secret-value --secret-id  my secret id


It says invalid choice.


  aws: error: argument command: Invalid choice, valid choices are:


and doesn't list secretsmanager as one of the choices or any variation on secretsmanager?

aws secretsmanager get-secret-value --secret-id  my secret id


was used in a video from 2018 

Similarly, this command doesn't work

and AWS help and AWS man don't contain secrets manager?
AWS secrets are still accessible via the CLI.

The link you provided goes to an old version of the AWS CLI.  Check out the latest version and commands here: https://awscli.amazonaws.com/v2/documentation/api/latest/reference/secretsmanager/index.html